You Shall (Not) Pass: Strategies for Third-Party Gatekeepers to Enhance Volunteer Inclusion

Volunteering appears to be a mechanism that can contribute to societal inclusion. As nonprofit organizations continuously seek more volunteers, opportunities for volunteer inclusion seem limitless. We argue that, in reality, it is not that simple. Volunteer exclusion derives from the failure to seek, recruit, and place potential volunteers with antecedents predicting non-volunteering. This article focuses on the “sending-organization” in dual volunteer management. We look at sending-organizations, such as a corporation or school, that organizes volunteer opportunities for its participants in a “receiving-organization,” i.e., the organization where the volunteer service is performed. Based on qualitative data generated from semi-structured and vignette interviews, we explore the crucial role that gatekeepers at the sending-organization play in the inclusion and exclusion of volunteers in receiving-organizations. We identify three strategies for these sending-gatekeepers to enhance volunteer inclusion: encouraging, enabling, and enforcing.


Introduction
Over the past several decades, volunteering has become more complex yet also more important for individuals and organizations (Sachar et al., 2019). Nonprofit organizations often have a never-ending quest for volunteers to sustain and expand their activities (Farmer & Fedor, 2001;Hager & Brudney, 2004). Besides its importance for nonprofit organizations, volunteering has also become valuable for other types of organizations. In education, for example, volunteering sends a signal of the ''merit'' of prospective students to prestigious universities . In the business world, volunteering showcases the involvement of corporations and their employees in corporate social responsibility (see Roza, 2016). On the other side, nonprofit organizations often have a neverending quest for volunteers to sustain and expand their activities (Farmer & Fedor, 2001;Hager & Brudney, 2004). As the need for volunteers grows, and organizations and governments continue to explore new ways of involving individuals in volunteering (e.g., community service at schools, welfarevolunteering), the possibilities to transfer volunteer energy into actual volunteering (Brudney & Meijs, 2009) appear limitless.
Yet, inclusion in volunteering is not so straightforward (Meyer & Rameder, 2021). Within this article, we use the term volunteer inclusion to refer to equal formal volunteering opportunities that are available to all individuals. Hustinx et al. (2010) called social inequality in volunteering a major challenge. Sachar et al. (2019) argue that volunteering actually exacerbates social exclusion and reproduces existing social hierarchies. In turn, social exclusion diminishes pro-social behaviors such as volunteering (Twenge et al., 2007). This potentially leads to an endless cycle of reinforced social inequalities. In their review of barriers to volunteering, Southby et al. (2019) state that value is lost as groups who stand to gain from and create most value for themselves by volunteering are most likely to be excluded. Scholars recognize that certain groups such as unemployed citizens, ethnic minorities, and physically disabled individuals are underrepresented in volunteering as a result of exclusion. This exclusion is practiced by organizational gatekeepers (Bonnesen, 2019), namely the individuals who are the first point of contact for prospective volunteers, and who direct them toward volunteering opportunities within nonprofit organizations.
Given that diversity within organizations reflects the dynamics in civil society, the under-representation of certain groups in volunteering is especially troublesome. Weisinger et al. (2016) stress the business case for diversity and recognize the importance of inclusion, noting that diversity can have meaningful impact on organizational performance and effectiveness. A diverse volunteer workforce increases the chances of beneficiaries being similar to volunteers (e.g., ethnicity, disability, religious orientation), which in turn could improve nonprofit services (Hoogervorst et al., 2016;McBride et al., 2011). Bortree and Waters (2014) argue that a diverse volunteer workforce strengthens the relationship between the nonprofit organization and the volunteer, and even improves retention of volunteers.
Addressing diversity and inclusion is also a moral imperative for nonprofit organizations. A social justice case for diversity and inclusion can be made as nonprofits should focus on reducing exclusion and marginalization (Weisinger et al., 2016). A sustainability case of volunteer inclusion has also been made. Brudney and Meijs (2009) argue that in order to sustain volunteer inclusion, new approaches to capturing volunteer energy are needed. They propose including individuals with non-volunteering antecedents as an approach to replenish volunteer energy.
Research finds that the managerial and organizational systems available to enhance inclusion in volunteering cannot usually compensate for the exclusion of volunteers (see, e.g., Eliasoph, 2009Eliasoph, , 2011. A primary reason is that civil society organizations increasingly focus on efficiency. As a result, volunteer recruitment is often aimed at approaching easily accessible volunteers who already possess the skills and backgrounds for the tasks at hand (Bonnesen, 2019;Dean, 2016;Meyer & Rameder, 2021). Volunteer recruitment aimed at enhanced inclusion can be considered more costly and accordingly less efficient. Brudney et al. (2019) elaborate on a promising way to favor participation over efficiency in volunteer recruitment. They introduce dual models of volunteer management. These dual volunteer management models involve two organizations that share the guidance of volunteers. There is a ''sending'' organization such as a corporation or school that arranges or organizes volunteer opportunities for its participants. Additionally, there is a ''receiving'' nonprofit organization, which offers opportunities where volunteers would perform their service. In these dual volunteer management models, two gatekeepers (one at the sending-organization and the other at the receiving-organization) control the access to volunteering.
In this article, we argue that gatekeepers in sendingorganizations can play a significant role in surmounting exclusion for two reasons. Gatekeepers in sending-organizations (hereafter sending-gatekeepers) might have the ability to reach individuals outside the scope of the receiving-organization. They may also have the ability to prepare individuals for volunteering. In other words, sending-gatekeepers have the opportunity to recruit, train, and place potential volunteers in receiving-organizations that otherwise would not have been recruited. The role of sending-gatekeepers merit attention as this study explores how to make volunteering more inclusive to diverse groups.
This study centers on the strategies sending-gatekeepers (''first gate'') can utilize to enhance volunteer inclusion in receiving nonprofit organizations. We explore the following research question: What strategies can sending-gatekeepers use to enhance volunteer inclusion in receiving nonprofit organizations? Our data emanate from ten semistructured interviews and eight subsequent vignette interviews conducted in the Netherlands with third parties characterized as sending-gatekeepers. The interviews identify strategies for achieving and enhancing volunteer inclusion in receiving nonprofit organizations.
By answering the research question, we make three contributions to the scholarly literature. First, the study advances knowledge of inclusion and exclusion in volunteering. We demonstrate that various gatekeepers constitute a central actor in the attainment of volunteer inclusion. We theorize a (new) more complex and dynamic process that can activate and access potential volunteers in the dual volunteer management models presented by Brudney et al., which heretofore ''have not received serious treatment'' (2019, p. 75). As policymakers increase their efforts to enhance social inclusion through volunteer participation , the strategies by which gatekeepers in these models manifest inclusion and exclusion of volunteer energy merit attention.
Second, the systematic mapping of nonprofit research by Ma and Konrath (2018) confirms the predominant stance of theory in predicting participation in volunteering on the one hand and various (desirably positive) outcomes of volunteering on the other (see for example Musick & Wilson, 2008;Smith, 1994;Wilson, 2000Wilson, , 2012. Ma andKonrath (2018, p. 1148) conclude that theories of volunteering ''predominantly focus on the preconditions, motivations, and consequences of volunteering.' ' Sachar et al. (2019) echo this view, concluding that volunteering research mainly focuses on its antecedents or consequences, while volunteering itself remains a ''black box.'' This preoccupation of volunteering research on ''who volunteers'' (Studer & Von Schnurbein, 2013) and on the outcomes of volunteering overlooks the activities of organizations in eliciting (or overlooking) particular types of volunteer energy. Understanding which individuals and communities are not accessed or actively recruited because they entail non-volunteering antecedents or backgrounds is an important building block toward a more inclusive volunteer workforce.
Third, most knowledge on volunteer exclusion is based on research at the individual level. By contrast, we shed unaccustomed light on the organizational side of volunteer inclusion and exclusion, as suggested by Sachar et al. (2019). We argue that current practices of volunteer management socialize volunteer managers to focus their recruitment attention on those individuals and communities that have ''volunteer antecedents'' (Studer & Von Schnurbein, 2013). These include antecedents such as higher education and income, which ease recruitment. Greater volunteer inclusion, however, requires volunteer managers to give attention to individuals or groups with ''non-volunteering antecedents.'' Non-volunteering antecedents include for example, an immigrant or unemployment status or disability.
Findings provide insights on the strategies of sendingorganizational gatekeepers that enhance volunteer inclusion. Our findings can have instrumental value for both sending-and receiving-organizations as well as governments. We conclude with a discussion of strategies to foster volunteer inclusion.

Volunteer Exclusion and Inclusion
Volunteer exclusion manifests itself both at the individual (i.e., volunteers) and at the organizational level (i.e., nonprofit organizations). Meijs et al. (2006) posit that individuals engage in volunteering according to their ''volunteerability,'' a concept parallel to ''employability'' in relation to paid work. An individual's volunteerability is based on their willingness, availability, and capability to volunteer. Volunteer energy materializes into actual volunteering only when nonprofit organizations adapt to the features of an individual's volunteerability. That is to say that although some individuals might have the appropriate levels of volunteerability, they only actually engage in volunteer service when they are approached by the right volunteer organization with a suitable volunteer job or assignment (Haski-Leventhal et al., 2018).
Introducing the dominant status theory of volunteering, Smith (1994) and Hustinx et al. (2010) show that individuals who possess more sociocultural and socioeconomic resources, such as high levels of education, wealth, and income, belong to the dominant status group of volunteering. Those with ample resources make up the largest share of the volunteer workforce. They are in higher demand by volunteer organizations  and are more likely to present themselves as prospective volunteers to nonprofit organizations (Smith, 1994). This is corroborated by Enjolras (2021) who argues that people are more likely to volunteer when their human, economic, and social capital are higher. Moreover, Handy and Cnaan (2007) find that individuals with more personal resources have greater ability to avoid or overcome social anxiety in approaching a nonprofit organization for volunteer opportunities.
While individuals with ample resources hold the largest share of the volunteer workforce and are in higher demand, the opposite holds true for individuals with restricted resources. According to Clary et al. (1996), the lack of personal resources affects the intrinsic or extrinsic motivations to become a volunteer. Dury et al. (2015), following Wilson and Musick (1997), agree that a lack of resources (e.g., low education and household income) present barriers to volunteering. Besides, some people face structural barriers such as time constraints or health issues (Sundeen et al., 2007). Negative perceptions of volunteering, negative attitudes toward volunteering, and the fear of being rejected are also reasons to not volunteer (Haski-Leventhal et al., 2018Warburton & Smith, 2003). Additionally, those who do not volunteer are more likely to believe volunteering requires specific knowledge and skills, resulting in their perception of being under-qualified, or that the skills they do possess will be worthless (Haski-Leventhal et al., 2018;Haski-Levethal et al., 2019). In sum, the lack of certain resources or personality traits Voluntas (2022) 33:33-45 35 (Ackermann, 2019) results in individuals (un)consciously self-selecting themselves as non-volunteers. Combined, these theories suggest that dominant status groups are more likely to self-select into volunteering for two reasons. First, because they possess the economic, social, and cultural resources that enable them to volunteer. Second, because these resources are associated with dominant status positions, they render high-status volunteers that are more desirable to nonprofit organizations. These theories help to explain that the volunteer workforce often consists of individuals who have, or believe they have, ample personal resources to serve nonprofit organizations. Consequently, nonprofit organizations seek individuals who belong to the dominant status group . This serves as a self-enforcing process of inclusion and exclusion of volunteers (see, e.g., Dean, 2016) which can be overcome, for instance, by adequate organizational support and better information (Boezeman & Ellemers, 2008).

Organizational Decision to (Not) Select Volunteers
Although both academic and practitioner literature seem to be obsessed with recruitment (Brudney & Meijs, 2009), research on inclusion and exclusion of volunteers in the volunteer selection and matching process from the organizational remains scarce. Given ''the mere fact of being asked to volunteer greatly increases the likelihood that people start to volunteer'' (Bekkers et al., 2016, p. 5), it is incomprehensible that the likelihood of being invited or asked to become a volunteer is not evenly spread (Handy & Cnaan, 2007;Smith, 1994).
Previous research provides ample evidence that individuals are typically asked to do volunteer work before they become active (see Bekkers et al., 2016). Surveys conducted by the Independent Sector Organization in the United States show that direct solicitation is a highly efficacious method of recruitment into volunteer service. For example, those asked to volunteer are much more likely to accept that invitation and to give more time (Musick & Wilson, 2008;Toppe et al., 2002). Most importantly, ''the influence of solicitation does imply that the 'decision' to enter into volunteering is also made in part by others than the prospective volunteer'' (Bekkers et al., 2016).
Volunteer organizations tend to target individuals with high ''participation potential'' in their volunteer recruitment (Musick & Wilson, 2008, p.290). That is, those individuals with positive volunteering antecedents. Participation potential relates to the dominant status and resource approaches to volunteering discussed earlier. Bonnesen (2019) finds that in addition to the pressures for efficiency, receiving-gatekeepers exclude different social groups based on the notion of finding the perfect volunteer. For instance, Miller et al. (2002) show that nonprofit organizations do not consider individuals with disabilities for volunteering roles. The authors show that nonprofit organizations even insert barriers to obstruct individuals with disabilities to become volunteers. We argue that nonprofit organizations can enhance volunteer inclusion if volunteer recruitment would deliberately target audiences with nonvolunteer antecedents.

Third-Party Model and Dual-Management Gatekeepers
Nowadays, volunteers are no longer only asked to volunteer by nonprofit organizations where the volunteer work is performed. The past decade has led to an increase in actors within the volunteering landscape. Traditionally, the volunteering landscape consists of the volunteers who give their time, the nonprofit organizations where volunteers perform their volunteer work, and the beneficiaries who benefit from the services provided by the nonprofit organization . Contemporary models of volunteer management conceive of more actors involved in embedding volunteer energy (Brudney et al., 2019;Hustinx & Meijs, 2011). It is no longer only the nonprofit organization that recruits and involves volunteers, but also schools and corporations , volunteer centers (Bos, 2014), and government agencies. The latter solicits volunteer service in exchange for welfare (Davis Smith, 2003;De Waele & Hustinx, 2019) and provides community service sanctions to offenders (Bazemore & Maloney, 1994).
These so-called third parties reap new sources of volunteer energy with different groups of individuals. In their third-party model of volunteering, Haski-Leventhal et al. (2010) propose that these entities expand the ways in which potential volunteer energy becomes ''activated'' or ''tapped'' and transformed into actual volunteer service. These third parties follow the functional re-embedding strategy trying to reintegrate, re-construct, or restore volunteering by mobilizing and enabling individuals to volunteer (Hustinx, 2010;Hustinx & Meijs, 2011). Sometimes these strategies are not without risk and can create negative consequences (Eliasoph, 2011) or support existing patterns of privilege (Wheeler-Bell, 2017).
To understand these new actors in relation to traditional actors, Brudney et al. (2019) articulated a Volunteer Stewardship Framework. Their framework proposes that the volunteer-activation process takes different forms and utilizes different management practices. They differentiate four basic volunteer models: membership, service, secondary, and intermediary. They distinguish volunteer models according to (1) whether volunteer administrators enjoy private access to volunteer energy, or if they must share access with other organizations (common pool); and to whether (2) the volunteer administrator has unitary control in the management of the volunteers, or this control is shared with another organization.
According to Brudney et al. (2019), the membership model accesses volunteer energy among their own members or constituents and transforms the volunteer energy into voluntary work within that same organization. In the service model, volunteer energy is activated among a common pool of potential volunteers by a nonprofit organization and is reaped by the same nonprofit organization to deliver products or services to the nonprofit's beneficiary group. These two models have a single management model: the sending-organization is the same as the receiving-organization. The other two models adhere to shared or dual volunteer management, which can be found in the third-party model of Haski-Leventhal et al. (2010). In the secondary model, sending-organizations such as corporations, schools, and government agencies access volunteer energy among their own members or constituencies and send them to receiving-organizations in the community. The same applies to the intermediary model (e.g., volunteer centers), although these actors do not have a private pool of potential volunteers.
In the secondary and intermediary models, two gatekeepers share volunteer management (Brudney et al., 2019). Sometimes, the gatekeepers in the sending-organizations have their own instrumental goal to have their constituents volunteer , for instance, the development of professional skills in corporate volunteering, community interest in school-based service learning, or employment in workfare schemes.
As elaborated upon earlier, volunteering excludes certain individuals when volunteer recruitment only targets those individuals with volunteering potential (i.e., having certain antecedents and backgrounds) (Davies, 2018;Musick & Wilson, 2008). Volunteer gatekeepers consider certain groups as inappropriate and inefficient audiences when they recruit for volunteers. Volunteer gatekeepers presume that individuals having non-voluntary antecedents (e.g., lower education or income levels) possess low levels of volunteerability. According to Studer and Von Schnurbein, nonprofit organizations are challenged ''to find the 'right ' volunteers'' (2013, p. 418), suggesting that volunteer recruitment entails volunteer selection and, hence, volunteer exclusion. While activities such as screening and matching volunteers are an efficient and effective strategy to meet organizational needs, they jeopardize volunteer inclusion.
To enhance volunteer inclusion, we argue that sendinggatekeepers can play a role in the shared volunteer models. Community service at schools , corporate volunteering (Meijs et al., 2006), obligatory forms of volunteering (Bridges Karr, 2007), and national days of service (Maas et al., 2020) can introduce individuals to volunteering. If sending-gatekeepers (also) include those with non-volunteering antecedents, these potential new volunteers can become aware of the value of volunteering and of the fact that they can contribute to the volunteer service. In that way, third parties can motivate those who would otherwise self-select not to volunteer or who would be excluded from the volunteer service. For instance, Roza (2016) finds that corporate volunteering motivates employees who otherwise do not volunteer. Kampen et al. (2019) examine volunteer programs wherein individuals are obligated to volunteer to receive welfare payments. These programs incite volunteer service from former or non-volunteers.
As volunteer gatekeepers control access to volunteer service by allowing or disallowing individuals to volunteer, we explore the strategies that sending-gatekeepers can use to enhance volunteer inclusion. We now turn to the methodology and data that inform our study.

Methodology Data Collection
As research on the phenomenon is scarce, our study adopts an exploratory qualitative research approach (De Boer & Smaling, 2011;Eisenhardt & Graebner, 2007). This case study approach is appropriate as it facilitates theoretical development and helps us to understand respondents' meanings and perceptions (De Boer & Smaling, 2011).
We collected data in a two-phase interview process consisting of semi-structured interviews in the first phase and vignette-based interviews in the second phase. We invited all respondents based on convenience sampling through an email-listing of practitioners, provided by the Association for Dutch Organizations of Volunteering (NOV). NOV encompasses more than 360 affiliated sending-and receiving-organizations. The solicitation began with a brief description of the study, followed by an invitation to participate in an interview. Our data emanate from 18 semi-structured and vignette-based interviews with 15 sending-gatekeepers in organizations that mobilize and send volunteers for volunteer service in receiving-organizations. Respondents had between 2 and 10 years of experience in these positions and worked at, for example, companies with corporate volunteering programs and volunteer centers that organize community service. Some respondents worked at organizations that specifically focus on stimulating volunteer involvement with groups with non-volunteering antecedents, while others target the population of prospective volunteers more generally. Three Voluntas (2022) 33:33-45 37 respondents participated in both phases of the data collection, resulting in 12 unique respondents. Interviews were conducted in Dutch, the native language of the respondents. 1 All interviews were recorded with consent of the respondents, and notes were taken by the interviewer during and immediately after the interviews.

Phase 1
Respondents in the first phase of the study were gatekeepers at sending-organizations. Five respondents worked in intermediary models as defined by Brudney et al. (2019) (e.g., representatives of volunteer centers) and five respondents in secondary models (e.g., representatives of corporations). We conducted one face-to-face, and nine virtual interviews; interviews ranged in length between 30 and 60 min. Interviews followed a semi-structured approach, where respondents answered both pre-determined and improvised open-ended questions (Jamshed, 2014;McIntocs & Morse, 2015). Interviews began with a brief description of the research, followed by questions about the interviewee's experience with intermediary and/or secondary management of volunteers, respondent's thoughts on how these shared volunteer management models might lead to the inclusion and exclusion of prospective volunteers, and how inclusion within volunteerism could be enhanced more generally. In the first phase of the data collection, respondents discussed strategies that their organizations implement to enhance volunteer inclusion. Respondents also shared their ideas on other strategies that enhance volunteer inclusion.

Phase 2
Guided by the first set of interviews and literature, we developed six vignettes representing various third-party models (three intermediary, three secondary) to conduct vignette-based interviews to prompt respondents (Jenkins et al., 2010). Following Spalding and Philips (2007), the vignettes were inspired by our initial interview data to assure the data's credibility. Vignettes are a technique used in in-depth interviews or focus groups that provide sketches or fictional scenarios, while still grounded in reality, whereby respondents are invited to respond to scenarios by drawing on their own experience. The presentation of vignettes results in collecting ''situated data'' (Bloor & Wood, 2006). Vignettes ''act as a stimulus to extend discussion of the scenario in question'' (Bloor & Wood, 2006, p. 183). An advantage of vignette interviewing is that it is less confrontational to ask interviewees to put themselves in the shoes of hypothetical characters, which can yield rich and sensitive data otherwise not available (Jenkins et al., 2010). Vignettes provide a valuable research tool for exploring people's perceptions, attitudes, beliefs, and meanings concerning specific situations (Barter & Renold, 1999;Hughes & Huby, 2002). They can ''meet the demands of rigor required of qualitative research'' (Wilson & While, 1998, p. 85) and have been documented as a useful research strategy for more than 25 years (Spalding & Philips, 2007).
The six vignettes we generated recounted hypothetical situations related to the inclusion or exclusion of volunteers. For instance, one vignette about the secondary model portrays a situation wherein only certain schools participate in the community service program despite it not being mandatory anymore. Another vignette on the intermediary model describes the methods of recruitment undertaken by a volunteer center. The vignettes were standardized to facilitate analysis and comparison across respondents. For this phase of the data collection, we conducted six vignettebased interviews with a total of eight respondents. Interviews were conducted via face-to-face (three), telephone (one), or video calls (two); all ranged in length between 45 and 90 min. The vignettes were presented in writing (Hughes, 1998) in the face-to-face interviews or were emailed during the (video) calls. Following the presentation of a vignette, respondents were asked a set of questions on levels of inclusion in the scenario, proposed strategies for further inclusion presented in the vignette, and their own additional proposed strategies for enhanced inclusion. In addition, the interviewer probed to gain further insights. The vignettes solicited discussion from respondents on the organizational strategies to enhance volunteer inclusion.

Data Analysis
The semi-structured and vignette-based interviews were digitally recorded and transcribed. The transcriptions and interview notes resulted in 118 pages of raw data after carefully excluding irrelevant sections of the documentations (e.g., exchanging pleasantries, digressing from main topic). These data were subjected to procedures commonly used in qualitative data analysis (Eisenhardt, 1989). Codes were generated based on a mixed approach between deductive and inductive analysis. On the one hand, we used a systematic inductive approach in which we analyzed the data closely and developed coding of the information (Gioia & Hamilton, 2012). On the other hand, the codes were derived theoretically, taking into account the research question of the study and the knowledge regarding the 1 Citations in our results are translated from Dutch to English. Quotes were first translated from Dutch to English by the first author and consequently translated back to Dutch by the second author to enhance data validity. Differences in translations were discussed and lasted until consensus was reached. topic. Theoretical saturation was determined when the analysis of the data generated no new codes (Strauss & Corbin, 1998). Eventually, codes with similar attributes, repetitive patterns, and consistencies were organized into broader, more comprehensive themes (i.e., strategies).
The first author coded all data, while the second author coded about half of the data. The two coders compared the coding schemes and discussed any discrepancies, leading to modifications of the coding scheme. For example, the coders noticed that the two coders viewed group activities as either a training for volunteers or an introduction for the receiving-organization. Ultimately, this code was split up into two codes: training for prospective volunteers and meet-and-greet for receiving-organizations.
Below, we present the findings from our study of interviews with sending-gatekeepers in the Netherlands.

Findings
All respondents agreed that oftentimes current mechanisms and processes to attract and place individuals in volunteering are not inclusive. In their experience, individuals with non-volunteer antecedents are often underrepresented, possibly as a result of not being asked to volunteer. Respondents recognize factors such as a person's neighborhood, income, social status, migrant background, employment status, religion, age, and mental and physical abilities. More importantly, our data identify three strategies that sending-gatekeepers could utilize to enhance volunteer inclusion: encouraging, enabling, and enforcing as presented in the coding scheme (Table 1) and elaborated on below.

Encouraging
To enhance inclusion, respondents mention the importance of recruiting potential volunteers, specifically individuals with non-volunteering antecedents. Some respondents mention this might start by changing the terminology and not calling it ''volunteering'' anymore, as the verb might be off-putting to non-volunteers. ''We call it doing something for someone or society,'' mentioned a respondent.
Multiple respondents talk about ways to teach people what volunteering is. They do this by going to locations usually frequented by individuals who have non-volunteering antecedents. They give guest lectures, inspirational sessions, and workshops about different types of volunteering, and what it means for volunteers and their community. Furthermore, respondents argue that finding spokespeople from the communities of non-volunteers will help: ''You need to break barriers and show them that volunteering is not scary, and that most people can do it [volunteering].'' Another method is to show what volunteering is by having potential volunteers shadow a volunteer for a few hours: ''We organize activities where current volunteers can bring others, so they can have that [volunteer] experience and might think: 'That might be nice to do.''' When it comes to recruitment, respondents call upon both cold and warm recruitment to attract potential volunteers. Cold recruitment includes methods like hanging up flyers, posting on (internal) online platforms, and using social media (mentioned only by respondents in the intermediary model). Respondents suggested that cold recruitment methods can ''work if this is the way individuals inform themselves.'' It was also noted that it ''is not just about putting flyers up in the right place, it also what happens to them next.'' Regarding warm recruitment, several respondents suggest that relocating warm recruitment efforts toward other neighborhoods, different schools or companies, disabled individuals, or other age groups could attract specific individuals who are normally excluded from volunteering. Most respondents mention that ''word of mouth'' is key to attracting new volunteers. One respondent observes: ''You need to go to the neighborhood center and speak to them when you are accompanied by someone who is already volunteering. Go to a mosque or a school. Find their friends.'' Another respondent emphasizes the personal touch: ''Personal contact, exchanging experiences: 'Come with me, so you can see what I do. If you like it, you can also apply, if not, you don't'. That is important.''

Enabling
The data suggest that sending-gatekeepers have the opportunity to enable both the prospective volunteer to volunteer and enable the receiving-organization to enhance volunteer inclusion.

Enabling the Volunteer
Several respondents suggest that in cases where prospective volunteers feel under-qualified, offering workshops or trainings on skills could be a method to enhance inclusion. Another respondent's idea is to ''organize group activities to get to know the [receiving-] organization and focus on personal development.'' Multiple respondents emphasize the importance of a good intake, where the volunteer's preferences regarding the (location of the) receiving-organization, volunteer task, job-length, and frequency are considered. ''When someone wants to join, they will do an intake here. Then we talk about 'Have you done this before? Why do you want to join? What are you looking Voluntas (2022) 33:33-45 39 for?''', states a respondent. Respondents also consider the importance of trial days, where prospective volunteers can find out if the receiving-organization and volunteer-role are a fit, before fully committing. Multiple respondents mention that prospective volunteers can be encouraged and feel more at ease with the introduction of a volunteer-buddy. For example, a respondent recalls: ''We prefer at least two people going somewhere [receiving-organization], because it is more fun.'' The respondent further explains that with asylumseekers a volunteer-buddy also helps to overcome the language-barrier: ''We also look at language, we try to always have someone join who can speak English…and ask the [receiving-]organizations to help them learn Dutch.'' Another idea is a volunteer-buddy directing prospective volunteers to receiving-organization: ''We have bicycle-volunteers and if they [prospective volunteers] have a volunteer-job, we have bicycle-volunteer who cycle with them to the [receiving-] organization.'' Respondents also mention some individuals might need (financial) support to start volunteering, for example, a small volunteer stipend or covering their travel cost. Another type of support suggested is allowing employees to volunteer during working hours.
Furthermore, our respondents introduce the concept of the ''third gatekeeper'' who sending-gatekeepers need to consider. This third gatekeeper is someone with autonomy over the prospective volunteer, for example, their parent or direct manager. Prospective volunteers might need their permission to start volunteering, meaning that the sendinggatekeeper needs to actively engage with these individuals as well.

Enabling the Receiving-Organization
To open up the receiving-organization for new volunteers, respondents suggest sending-gatekeepers to organize informational sessions to showcase what these ''new'' individuals have to offer. For example, by organizing meet & greets or group activities at the receiving-organization. This way, organizations might learn that the ''perfect volunteer'' could be found outside of their usual target group and will ask people with non-volunteering antecedent to join their organization in the future. A respondent suggests: ''I think it is our job to let [receiving-]organizations know: 'Something new is coming. We will keep you posted. It is about this and this target group, just think about it already. If you have any questions about it [new prospective volunteers], we will answer them.' This way the [receiving-]organization know what's coming.'' One respondent highlighted that their sending-organization does not allow the receiving-organizations to deny individuals who applied to volunteer. Other respondents recommended negotiations between the sending-and receiving-organizations to clarify and cement their commitment to volunteering.

Enforcing
A third, perhaps contested, strategy is mandated volunteering. Several respondents mention that mandated volunteering opportunities can enhance the inclusion. The goal of inclusion is enhanced by making participation in corporate or community service volunteering programs mandatory for all employees or students. All respondents agree that enforcing volunteering will help enhance volunteer inclusion. Yet, respondents question the durability and effectiveness of these measures. Our data indicate that most respondents indicate that obligated volunteering might have negative consequences on the volunteer organization, its regular volunteers, and/or its beneficiaries. Respondents note that negative consequences arise if ''the volunteer does not really want to be there.'' Although enforcement strategies could be practiced by gatekeepers of sending-organizations to pursue more inclusion, respondents raise caution that receiving-gatekeepers may remain wary.
On the other hand, some respondents could recall instances in which mandated volunteering transformed into a positive and sustainable relationship between the volunteer and the receiving-organizations and their beneficiaries. For example, a respondent notes: ''One time two girls volunteered at a monastery. I was called by their school asking me where the girls were…They were not at school and not at home, so I thought maybe I should call the monastery. It turned out the girls were there again even after their community service ended…They were like: So what?! This is important, I'm not just going to stop helping.'' Another respondent recalled an example of a boy who continued visiting an elderly man, because the boy said; ''If I quit no one will visit this man. That would be very bad, so I am just going to continue visiting.''

Discussion
Despite increasing importance of volunteering for individuals, organizations, and society (Sachar et al., 2019), the lack of inclusion and representation of certain groups in volunteering is troublesome Meyer & Rameder, 2021). Research shows certain individuals tend to be excluded from volunteer opportunities based on their own perceptions about non-volunteering antecedents, and perceptions by receiving-organizations. Non-volunteering antecedents include a lack of economic, social, and cultural resources needed to engage in volunteering (e.g., Hustinx et al., 2010;Smith, 1994). The dominant status theory of volunteering Smith, 1994) suggests that individuals who belong to the dominant status group of volunteering possess more sociocultural and socioeconomic recourses (e.g., high levels of education, income). These individuals are more likely to find volunteering opportunities on their own. Our study affirms this view and finds similar results highlighting that individuals with nonvolunteering antecedents are not being asked.
In this research, we argue that sending-gatekeepers in third-party models can be part of the solution in creating a more inclusive volunteer workforce. Grounded in the experiences of the gatekeepers we interviewed, our data provide a more nuanced picture of volunteer inclusion than currently portrayed in the scholarly literature. The strategies point to the role played by third parties and receivingorganizations in attracting, or overlooking, certain individuals in volunteering. Our results indicate that sendinggatekeepers can use three overarching strategies to include more individuals with non-volunteering antecedents: encouraging, enabling, and enforcing.
Our three strategies suggest that the sending-gatekeeper at schools, companies, and volunteer centers for instance can broaden their pools of potential or prospective volunteers for receiving-organizations by shifting attention to those less likely to volunteer, i.e., those with non-volunteering antecedents. This connects well with the concept of volunteerability introduced by Meijs et al. (2006), as research shows that with the right methods individuals with non-volunteering antecedents could be more inclined to volunteer with the right barriers removed (Haski-Leventhal et al., 2018).
An individual's willingness to volunteer is based on their perceptions of, attitudes toward, and motivations to start volunteering. Willingness can be increased by strategies aimed at encouraging, for example, changing terminology or explaining what volunteering is. Capability refers to the (perceived) skills and competences a volunteer has . Enabling strategies, such as workshops on personal development, can help increase the capability within volunteerability. Availability is the perception of time an individual has to volunteer; it can be increased by all three strategies. Enabling and encouraging can change perceptions of availability. The most powerful strategy is enforcing as it influences willingness and availability almost in a binary way. For instance, corporate social team building activities during worktime are accepted as obligatory by the employees.
Haski-Leventhal et al., (2018, p. 1152) state that ''countering the barriers that prevent people from volunteering may, in fact, be more effective than merely appealing for individuals to volunteer more often.'' This view is corroborated by our data as our three strategies of encouraging, enabling, and enforcing will help both individuals and organizations to overcome those barriers. We show that especially sending-gatekeepers can be very powerful in removing these barriers.
Some of the excluded individuals do volunteer informally, as less human capital is needed for this Wilson & Musick, 1997). The encouraging and enabling strategies aim at deformalizing volunteering, minimizing the distance between informal and formal volunteering.
The third strategy for enhanced inclusion, enforcing, is however a contested one. Like Bridges Karr (2007) and Kampen et al. (2019), our data show that obligatory forms of volunteering can introduce new individuals to volunteering. Similar to Eliasoph (2009, 2011) and Lichterman (2006 our respondents do question whether this form of volunteering is effective, as volunteering without intrinsic motivation could be seen as not pure. Respondents also doubt the sustainability of mandated volunteering, though they do present positive stories of individuals continuing their volunteer service after obligations are lifted. Ultimately, enforcing is contested on a normative level, but can seemingly enhance volunteer inclusion. Dunn et al. report that studies find several barriers to recruitment, one of which is resource constraints (2020). This leads to the question why nonprofit organizations would use limited resources to focus on recruiting individuals with non-volunteering antecedents. In dual-management models, the sending-gatekeepers are responsible for the recruitment tasks and also carry the cost. This means that third-party gatekeepers are, in fact, a very costefficient and effective way for nonprofit organizations to include volunteers with non-volunteering antecedents.
Although we hope that our findings may lend new insight into understanding the organizational sources and possible remedies of volunteer exclusion, we must be cautious in generalizing our findings to other locations and contexts. Our qualitative data emanate from the Netherlands, a country that boasts a strong volunteering tradition where almost fifty percent of the adult population volunteers at least a few times a year (Arends & Smeeds, 2018). We are cautious in extending our findings to countries with different volunteer histories or traditions. In addition, as the secondary and intermediary volunteer models are still quite new in the Netherlands, our sample was limited (12 unique respondents), with the respondents often identifying similar issues and expressing convergent approaches. Respondents also noted that the subject of our study, inclusion in volunteering, is a sensitive matter. This could have limited openness in their responses and evoked socially desirable responses.
We encourage further research to deepen our understanding of non-volunteering antecedents. As Haski-Leventhal et al. (2018) explain, most knowledge regarding who does not volunteer, and knowledge on policies to convert non-volunteers into volunteers is based on (former) volunteers who have not volunteered in the past year. In many cases these individuals have volunteered before and are not part of those perennially excluded. Yet, based on our interviews and recent statistics in the Netherlands, even in a country with half of the population volunteering, large groups of people consistently do not volunteer.
Our strategies focus on what sending-gatekeepers can do to enhance inclusion in volunteering. In this scenario, receiving-organizations would need to start thinking more proactively about how to manage the new workforce diversity. This merits attention as previous research shows that volunteer inclusion is associated with improved needsatisfaction, competence, productivity, and retention (Boezeman & Ellemers, 2009). Future research might explore how to effectively manage volunteer workforce diversity in receiving-organizations.
As our research suggests three strategies for gatekeepers in sending-organizations to enhance volunteer inclusion, future research might also explore whether these strategies should be applied separately or together. Another question for research is whether these strategies should be tailored to specific target groups and how to identify those. Future research could also expand knowledge on the potential negative effects on strategies for enhanced volunteer inclusion. Some literature highlights the negative effects of obligating volunteering. Volunteer obligation might thus not lead to sustainable volunteer energy, and it might affect adversely the organization, other volunteers, as well as beneficiaries. While strategies for volunteer inclusion may open organizations to this activity, unintended dilemmas can also result (Eliasoph, 2009(Eliasoph, , 2011Lichterman, 2006), warranting further research.
Nevertheless, failure to attract and renew potential sources of volunteer energy, particularly from excluded individuals, may threaten the new reproductive capacity of the volunteering commons (Brudney & Meijs, 2009). No source of volunteer energy can-or should-be overlooked. Volunteer gatekeepers at sending-organizations in third-party models of volunteering have a unique vantage point in enhancing volunteer inclusion.
Funding No funding was received for conducting this study.

Declarations
Conflict of interest The authors have no relevant financial or nonfinancial interests to disclose.
Ethics Approval All procedures performed in studies involving human participants were in accordance with the 1964 Helsinki declaration and its later amendments or comparable ethical standards.
Informed Consent Informed consent was obtained from all individual participants included in the study.
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