Introduction

Studying child well-being from a broad perspective that goes beyond traditional views and incorporates new and interdisciplinary aspects is a trend that has emerged quite strongly in the field of social sciences in recent decades. This interest has arisen in a context of profound changes in the understanding of children and childhood, supported by at least three processes (Bruck & Ben-Arieh, 2020): the United Nations Convention on the Rights of the Child (CRC); the development of the so-called New Sociology of Childhood (Qvortrup, 1999; James and Prout, 1997; Gaitán, 2006); and the theory of Child Development Ecology based on a bioecological model of human development (Bronfenbrenner & Morris, 1998). In this context, the literature on child well-being has grown significantly and has spread rapidly across different approaches and disciplines. As a result, in our view, it is essential to have a systematised framework of study in order to develop the analysis further.

Two essential aspects of this field of work are considering children as active agents in the very definition of the concept and incorporating new approaches that are capable of enriching a more traditional economic-based and adult-centred conceptualisation, such as those that explore subjective approaches to well-being (Ben-Arieh, 2012; Casas, 2011; Casas, 2019). To deepen this line of research, the capability approach (Sen, 1985) in connection with the new Sociology of children and childhood constitutes a valuable tool since it provides essential elements for an analysis of well-being from a multidisciplinary, relational and interconnected perspective on childhood.

The capability approach (CA) focuses on what people are really capable of being and doing (ends) and not just on the resources they have and the public goods they can access (means). This implies asking, "What are people really able to do and what kind of person are they able to be?” and leads to a normative commitment to conceptualising well-being in terms of capabilities (what people can do and be if they so choose) and functionings (what they are actually achieving in terms of beings and doings, the capabilities that have been realised) (Robeyns, 2017; Robeyns & Byskov, 2021). As a result, the CA involves a twofold notion of well-being: achieved well-being (focussing on functionings) and well-being freedom (connected to one’s capability set) (Sen, 1992).

From this approach, well-being is understood as the set of opportunities a person has to choose and make a life that they have reason to value. The focus is on the capabilities (also referred to as real or substantive freedoms) they have to decide, for good reason, for or against the realisation of certain ways of living their lives (functionings-outcomes). Furthermore, the CA is equipped with a theoretical tool that can be used to systematically analyse the relationship between subjective assessments and social contexts, the concept of "adaptive preferences" (Fegter & Richter, 2014). In addition, the notion of “evolving capabilities” (proposed by Biggeri et al., 2011; see also Biggeri & Santi, 2012) addresses how the opportunities, capacities and the agency evolve over time in a dynamic process. It is particularly useful for children (although probably also interesting for adults) as it acknowledges the dynamic and complex process of interaction between resources and individual and social conversion in feedback loops that reshape, at every stage, children's capability set.

Concerning childhood, “the Capability Approach is a normative framework that can be used to evaluate children's issues, children's issues may also challenge the CA framework itself and force us to revise it" (Comim et al., 2011, p. 5). We believe that, following Sen's approach, the human development of children can be seen as "an expansion of capabilities" (Sen, 1999; Kellock & Lawthom, 2011; Fegter & Richter, 2014). Therefore, although the CA concern is with the "expansion of capabilities" of children, it is not primarily based on an idea of childhood as developing into adulthood (becoming) but, rather, on the idea of a continued expansion of freedom (present and future). Nonetheless, some authors highlight the importance of safeguarding both children’s well-being and well-becoming (Peleg, 2019) and suggest that the functionings and capabilities that matter should be selected considering well-being and well-becoming as guiding principles (Schweiger & Graf, 2015). This implies focussing on the fundamental character of the “capability to develop” to become capable of "doing and being" in new and rapidly expanding ways (Chawla, 2015; Gardner, 2015).

Accordingly, taking into consideration aspects valued by children as essential to living a good life is one of the new elements incorporated in these types of analyses (Domínguez-Serrano & del Moral-Espín, 2018). One of the strengths of this approach is that it offers a concept of well-being that brings together the theoretical perspectives of both structure and subject (Fegter & Richter, 2014). It considers children as recipients of freedoms, but not exclusively (Biggeri et al., 2006). Well-being is also described as a phenomenon that children not only experience (or not) but also create themselves (Kellock & Lawthom, 2011). Using a CA means that it is necessary (although the consensus on this point is not absolute) to include children's standpoint on their well-being and consider the information they generate as the basis for evaluating their well-being. This does not imply that they are the only "experts" on their well-being, nor that no other views should be included in the evaluation. Indeed, it is essential to do so in a way that links the structural and subjective dimensions, looking at the positive freedoms necessary to decide how one wants to live one's life (Sen, 2004). In this sense, applying the CA to children implies positioning oneself in favour of their capacity for self-determination (Ballet et al., 2011; Brando, 2020; Hart & Brando, 2018). Despite this, not all studies using a capabilitarian perspective are necessarily participatory; in many cases, they continue to use indicators defined by experts, without much input from local, heterogeneous communities (Fegter & Richter, 2014; Dalyot & Dalyot, 2018).

Among the elements that have traditionally received less attention and are not present in the most common measurement are activities that transcend an economic-centred vision and, thus, incorporate aspects from a multidimensional perspective. CA is very well-equipped for analysing these activities, and dimensions more linked to the personal, caretaking, and emotional spheres are fundamental for the individual and collective comprehension of children and society as a whole.

For this purpose, we systematically reviewed the existing capabilitarian literature on children and childhood. As a result, this article is organised into distinct sections. The first one addresses the methodology we followed to develop the bibliographic review. The following section shares the results of this systematisation, exploring the type and year of publication, the country of focus, the specific theme addressed, and the methodology used. After that, we present a more detailed review of the spatial focus, the methodologies, the dimensions and the intersectionalities of a selection of the 36 documents directly related to the theme of well-being. Most of them include the word "well-being" or "wellbeing" in the title and/or in the keywords. In addition, of course, the notion of well-being was central to their argumentation.

Systematic Review: Method and Results

This article aims to respond to the need for systematisation mentioned above by reviewing the existing literature that uses CA to study children and childhood and, specifically, child well-being. For this purpose, the most relevant international databases, Web of Science (WOS) and Scopus were examined. In addition, to try to include a broader range of research, a detailed analysis was carried out of the bibliography compiled annually by an important institution in the field, the Human Development and Capabilities Association (HDCA). Until recently, this compilation was published in the Journal of Human Development and Capabilities. We did this to include non-indexed literature but still relevant to the topic. Below, we summarise the process we used to analyse each database.

This revision has an international scope and uses English as the primary language, although it includes some French, German and Spanish texts. In principle, we were interested in all kinds of works: working papers, articles, book chapters, books, papers and proceedings. We analysed the period 2000–2020, two decades in which there has been an evident boom in literature in Children and Childhood Studies and the CA. Due to the high volume of published works, it was crucial to delimit the object of study carefully. Thus, the goals that we set out for this search were:

  1. (1)

    To examine the definitions of child well-being compatible with a multidisciplinary and comprehensive vision.

  2. (2)

    To examine the existing literature on the CA applied to children.

The methodology used for the analysis in WOS and Scopus was structured in the following phases (see Fig. 1):

Fig. 1
figure 1

Phases of the search and analysis process

After verifying the relevance of the proposed revision, systematised searches are carried out, defining search equations around the concepts of `children’s capabilities’ focused on the field of Social Sciences. For this purpose, we used the following search equations:

Capability Approach and Childhood:

$$\mathrm{TITLE}:\mathrm{TI}=(\mathrm{Review}\;\mathrm{AND}\;(\mathrm{boy}\ast\mathrm{OR}\;\mathrm{girl}\ast\mathrm{OR}\;\mathrm{child}\ast)\mathrm{AND}\;\mathrm{Capabilit}\ast)$$
$$\mathrm{ABSTRACT}:\mathrm{ABS}=(\mathrm{Review}\;\mathrm{AND}\;(\mathrm{boy}\ast\mathrm{OR}\;\mathrm{girl}\ast\mathrm{OR}\;\mathrm{child}\ast)\mathrm{AND}\;\mathrm{Capabilit}\ast).$$

The search generates some results that need to be filtered according to the following criteria: (1) eliminating duplicates; (2) detecting works belonging to areas that are not pertinent to the object of study (epidemiology and medicine); and (3) identifying works that, although compatible with the object of study, are not relevant because of their different subject matter (capabilities identified with their acceptance in the educational environment or especially studies regarding high abilities).

In order to delve deeper into the literature connected to the CA but not indexed in the previous databases, we searched the bibliographies that the HDCA presents annually. The HDCA bibliographies we examined covered the period between 2004–2018.

After the various filtering processes, the final sample to be filtered came out to 121 (120 plus one that was a duplicate) in WOS. In the case of Scopus, filtering was done by focusing on the concept of "well-being", which limited the result to the 190 documents that would constitute the basis for the next phase of the research process. After various filters to delete documents already collected in the previous search, we retained 173 documents. We need to add that the review of the bibliography published by the HDCA started by examining the 14 documents, which contained 914 references. Finally, 34 of them meet our search criteria.

After unifying our databases, the result was 166 documents to be analysed. Some clarifications need to be made about them. First, an Erratum was eliminated because it was not relevant when systematising the results, so finally, 165 documents were considered. Of these, there were two book reviews, one of them discussing a book that was also included in the search results, and the other appraising a book that included relevant topics in one of its chapters but not in the rest of the book and, hence, it was not included in the database. Some books are relevant in their entirety to the study, and others only include some related chapters. Thus, in the final review, four complete books were considered. In order to avoid duplicating the information that would result from considering both the book and its chapters, we decided to analyse each one of the book chapters independently instead of the whole book. Therefore, the chapters of books analysed may belong to the same book (of the four commented above) or to another one that does not appear in the database. Concerning the analysis, it is also worth noting that one document consisted of research notes.

Once the initial phase of the search with its various steps was completed, we wished to review works that were more directly aligned with the object of study. Therefore, the final selection of documents took into account the following exclusion criteria related to the object of study: 1) Focus is on medical condition, 2) The focus is on the well-being of parents or adult people, 3) There is no specific analysis of children as a subgroup; and 4) It is not possible to have the English version of the document.

Using this criterion resulted in 144 documents which are analysed in the following section.

Analysis and Systematisation of the Results

The 144 documents that emerged from the systematised search constitute a set of essential materials for anybody who wishes to familiarise themselves with literature that analyses childhood from the CA. The documents can be organised according to their type, as seen in Table (Table 1).Footnote 1

Table 1 Types of documents in the two main databases

Even though the bibliographic review began in 2000, we did not find many relevant results until 2005–2010. Indeed, there has been an exponential growth of pertinent publications, in particular articles, in recent years, proof of the growing interest in the subject within international and interdisciplinary research (Fegter & Richter, 2014). However, despite the theoretical and methodological advances, empirical applications of the CA are still scarce (Steckermeier, 2019) (Graph 1).

Graph 1
figure 2

Types of documents by years of publication. Source: Own elaboration

In addition to classifying the documents by year of publication, we were interested in examining three other essential aspects: the country the study was focused on, the specific theme and the methodology. Concerning the first of these aspects, it is noteworthy that despite the traditional common association of the applications of the CA to impoverished countries or the Global South, we found that many were conducted in Western countries. This was especially true when we focused on studies examining specific contexts or collecting empirical data. This finding is especially relevant because it coincides with a more general tendency that we are witnessing of scholars in the Global North incorporating and using approaches and methodologies that were previously more established in countries of the Global South (Table 2).

Table 2 Articles by country

We found few studies carried out in Latin American countries, which may be explained by the fact that some of the relevant literature may be in Spanish. Specifically, only three studies discuss experiences in Colombia, Nicaragua, and Mexico and seven other studies that comparatively analyse the situation in various countries and include several Latin American countries. Similarly, there were 14 works, plus another seven made up of comparative studies, which referred to countries in the African context. The remaining studies, consisting of more than 30, were in Asian countries.

The second element considered was the theme or topic of the articles (Table 3). The frequency of the topics did not seem to be associated with the publication year. It should be noted that some titles were counted several times because their themes were multiple and not exclusive. Among them, education is the most advanced topic, focusing on the right to quality education and well-being. However, for the porpoise of this paper, it is also worth highlighting the articles that refer to well-being in a more general sense and to which we will refer later.

Table 3 Principal topic of the article

Third, we were interested in analysing the methodology used in the documents examined (Table 4). In this case, we included both articles and book chapters. Interestingly, although a significant number of the documents relied on theoretical bibliographic analyses, others described a diversity of methods and methodologies.

Table 4 Documents by methodology

Therefore, the analysis confirms that CA is a multimethod approach (Graph 2). Bibliographic and quantitative methods seem to be the ones that remain all over the period, although qualitative articles gained a place over the last decade.

Graph 2
figure 3

Articles by methodology and years. Source: Own elaboration

In addition to the three aspects mentioned above, we thought it would be pertinent to note what kind of diffusion the articles had. For this purpose, we catalogued the journals in which they were published. The publications appeared in a total of 63 different journals, and Table 5 shows those in which there was more than one article, which in many cases is due to it being a special issue. This gives an idea of the dispersion of the subject matter in different types of publications, making a compilation of information of this type very beneficial for those working in the field.

Table 5 Journal in which the articles were published

The results highlight the openness of Education journals to the CA, which is coherent with the predominance of papers on educational matters. However, the main objective of our paper is child well-being. For this reason, in the following section, we will focus on a more detailed analysis of the 37 papers classified under the topic 'well-being'.

Children, Well-Being and Capabilities

Acknowledging the multifaceted dimension of child well-being and its complexities as a research topic is essential. Over the last decades, significant methodological and conceptual progress has been made concerning different aspects of the notion and the indicators to measure it (Ben-Arieh et al., 2001; Ben-Arieh, 2005, 2008): there has been a clear move from a focus on minimum standards for children (survival indicators), to a broader concept connected to the idea of the quality of life and its implications for children’s lives. This implies focusing on positive aspects of their well-being and not only on thresholds determined by the absence of negative (mainly material) aspects. In addition, the increasing consideration of children as actual “beings” and not just as “becomings” has favoured a further move to the focus on their present lives' well-being and not only on what will affect their future adulthood. A necessary parallel development has favoured a wider recognition of the ecological diversity of children's lives and the need to incorporate new domains and subdomains into the analysis.

Capabilitarian studies addressing child well-being appear to have gained prominence among high-impact journals in the last decade, especially since 2015 (see Table 6). However, there are some pioneering papers almost a decade earlier, such as that of Biggeri et al. (2006) and Di Tommaso (2007). In 2011, the editors of the book Children and the Capability Approach (Biggeri et al., 2011) stressed in the introduction that the CA "has not yet adequately engaged with children's issues, although much has been written about education generally from this perspective" (Comim et al. 2011, p. 4). In this sense, they state that the book's contribution is that it "develops the capability approach (CA) as a conceptual framework for understanding children's well-being" (Comim et al. 2011, p.3). Fegter and Richter (2014) only three years later published their clarifying chapter "Capability approach as a framework for research on children's well-being," where they state that the CA:

is receiving a lot of attention in research on child well-being. The approach seems to be particularly appropriate for countering the problems and challenges that are emerging for research in this field from the perspective of New Social Childhood Studies (NSCS). (Fegter & Richter, 2014, p. 379)

Table 6 Documents by countries of focus and year

Specifically, the text addresses the issues of adaptive preferences, freedom and choice, and the "here and now" (being and becoming), and then reviews and comments on a significant number of studies on child well-being from a capability approach. In this section, we will begin with that review and proceed to update it. The total number of works analysed that refer specifically to well-being is 37. One additional book that is necessary to mention is Children and the Good Life (Andersen et al., 2010). It includes a specific section, Part II, on the Capability Approach that relates it (in particular Martha Nussbaum's ideas) with the principles from New Social Childhood Studies (Clark & Eisenhuth, 2010). Moreover, it offers a review of the empirical analysis based on the CA and elaborates on the notion of "evolving capabilities" (Biggeri et al., 2010) and on the perspective of subjective well-being (Ziegler, 2011).

Geographical Areas and Well-Being Research

The documents analysed refer to different geographical contexts. Table 6 shows the number of documents by country of focus with the year of publication. Although the pioneering one addressed the Indian context (Di Tommaso, 2007) soon, the approach was transferred to study mainly European realities.

As shown in Table 6, European countries are overrepresented. However, this does not dilute capabilitarian scholars' commitment to tackling poverty. Poverty and deprivation are one constant issue within well-being papers addressing both Global North and Global South contexts. In most cases, this analysis focuses on specific countries. Only a few studies (therefore, here is a gap to fill in) offer cross-country evaluation. Within the European context, D'Agostino et al. (2018) addresses the effects of the 2008 economic crisis on the well-being of children by reflecting on the responses that various welfare systems offered to common challenges. The author studies how, in the European context, the capabilities of children living in Greece and Italy, whose well-being at the beginning of the crisis period was lower than that of children living in France and the United Kingdom, suffered much more during the financial crisis. Both Greece and Italy are familiarist welfare regimes, and both strongly reduced the proportion of state support to families during this period. In parallel, Wilmes and Andresen (2015) propose an explorative comparison of child Well-Being in Nepal and Germany and call for more open ideas about what constitutes and composes (good) childhood in the different and non-western contexts. With a broader global approach, the International Survey of Children’s Well-Being “Children’s Worlds Study” (ISCWeB), a worldwide research survey on children’s subjective well-being, is the base for two papers (Steckermeier, 2019, Raciti & Vivaldi Vera, 2019). However, the representative data collected by this study offers great potential for studying children’s own perceptions and evaluations of their well-being, their daily activities and time use.

Spaces for the Well-Being

Another possible focus of analysis addresses how the CA helps investigate well-being around specific spaces. The most frequently addressed are educational spaces: schools and schooling (Biggeri & Santi, 2012; Hart, 2009; Hart & Brando, 2018; Kellock, 2020; Kellock & Lawthom, 2011; Terzi, 2014). The CA is described as a paradigm that contributes to the design or evaluation of different educational models, considering whether they promote children's agency, participation rights, and human flourishing. Furthermore, followings the previous elaboration on young people’s capability to aspire (Hart, 2012, 2016), Hart and Brando (2018) consider schools as spaces that enable children’s exploration and development of the values and aspirations that promote agency and well‐being and agency.

In addition to school, other settings where children spend most of their time are family and the neighbourhood. In this sense, considering safety as one of the fundamental domains for children's well-being, research has also focused on the importance of discriminating between safety in different areas of life: home, neighbourhood, and school, analysing the link between agency and safety (Steckermeier, 2019).

Other studies address how access to nature (in relation to urban planning) contributes to well-being and health (Chawla, 2015). In the same strand, Babb et al. (2017) adopts the CA to understand how Australian children's movements in their neighbourhood environment support their well-being. The results show substantial travel limitations and children's independent mobility, which contrasts with the positive view of the neighbourhood they have.

Methodological Approaches

Regarding methodology, the papers employ a variety of analytical methodologies. However, as shown in Table 7, the empirical application of the CA from a quantitative perspective has attracted the most attention.

Table 7 Well-being documents by methodology

These quantitative studies often opt for the selection method Alkire (2008) proposed, which involves using available data to select dimensions or indicators. This is the system Pedace (2009) used to approach the study of the functionalities linked to the well-being of children and adolescents in the United Kingdom or by the del Moral-Espín and Domínguez-Serrano (2020) for selecting indicators in Spain.

Some of these quantitative studies have explicitly focused on the well-being of children living in poverty, trying to understand it beyond merely monetary deprivation, for example, the work of Potsi et al. (2016). It pertains to the Italian context but could be replicated in other contexts by using the EU-SILC survey. In the Taiwanese context, Lin and Chen (Lin & Chen, 2017; Chen and Lin, 2020) focus on the reality of children and adolescents living in poverty in Taiwan and identify four possible states of well-being: guaranteed well-being, functional deprivation, capability deprivation and double deprivation. Their conclusions highlight that the situation of deprivation of capabilities is more complex to overcome than other forms of deprivation (Chen & Lin, 2020). In the case of Mexico, Valadez-Martinez (2016) analyses the impact of conditional aid programs, concluding that improvements in family income around the time of birth are positively associated with the psychological, cognitive, motor and emotional well-being of children from 4 to 6 years of age. Raciti and Vivaldi Vera (2019) also study the impact of conditional transfers but, in this case, analyse a pilot project in Italian cities and focus on children and adolescents' emotional well-being. To this end, the authors developed a Children's Standard Well-being Index based on the system of children's rights.

Concerning qualitative research, beyond the more traditional methodologies based on interviews and ethnography, visual methods are also applied. For example, in addressing well-being in the educational setting, Kellock and Lawthom (2011) conceptualise capabilities in collaboration with elementary school children using visual and photo-voice methodologies to engage and discuss with children and capture alternative creative frameworks of well-being and capabilities. Kellock (2020) has recently developed further this work by creating a dialogue between the CA and community psychology.

Other authors stress the value of finding a balance between ethnographic and experimental/correlational designs, developing a complementarity in mixed methods (Chawla, 2015). Apart from those already mentioned by Andresen and Fegter (2011) or Domínguez-Serrano et al. (2019), this type of approach remains a minority. However, it seems to be very useful to analyse the mobility or interaction of children in a specific territory (Babb et al., 2017)’. Emphasising the participatory aspects, Dalyot and Dalyot (2018) propose using georeferencing and collaborative mapping practices to explore and monitor child well-being and generate, through this process, data that is "owned" by the community but shared as public domain, available for public access.

Bibliographic studies tend to have an unspecified focus instead of addressing contextualised children’s realities. Many of these papers are particularly useful for comprehending the debates around children's agency and the CA (Hart, 2009; Hart & Brando, 2018; Fegter & Richer, 2014; Biggeri & Santi, 2012; Cabezas & Schweiger, 2016). Hart and Brando (2018) stress that the development of children’s agency is a fundamental goal of education and a well‐being achievement. Stoecklin (2019) incorporates a participatory tool (the actor's system) and points out methodological challenges in converting children's right to be heard into a real capability to participate. The analysis shows how language itself can be a conversion factor in implementing the right to be heart. In light of this, the importance of designing research protocols that emphasise children's agency is highlighted. The consideration of child well-being together with child well-becoming permeates Biggeri and Santi’s (2012) exploration of the potentialities of the pedagogical approach Philosophy for Children and Cabezas and Schweiger’s (2016) work around the ethical issues related to girl's bodily integrity.

Dimensions of Well-Being

The papers address a range of dimensions related to well-being. One key point is that capabilitarian conceptualisations of well-being differ from the dominant utilitarian views and measurement of well-being based on the accumulation of resources and wealth by individuals, households and nations (Hart, 2009; Kellock & Lawthom, 2011). The conception of children’s “good life” in many capabilitarian documents follows the Aristotelian tradition of not restricting well-being to the material aspects of life and revives Aristotle's notion of eudaimonia or happiness, often translated as 'human flourishing' (Fegter and Richter, 2014; Chawla, 2015; Dominguez-Serrano & del Moral-Espín, 2018; Raciti & Vivaldi Vera, 2019).

We identified a set of papers that sought to establish participatory definitions of the dimensions that comprise well-being. They included children as participants in the process of identifying a set of capabilities relevant to well-being. In this line, we found the pioneering paper by Biggeri et al. (2006), developed from the work done with children participating in the "World Congress of Children on Child Labour" held in Florence in May 2004. The authors presented a survey-based methodology for conceptualising and identifying, using a bottom-up participatory approach, a list of capabilities relevant to children. According to their findings, education, love, and care were the most relevant capabilities for children. We also found the works of Anich et al. (2011), conducted in England, Kellock and Lawthom (2011) carried out in Uganda and Domínguez-Serrano et al. (2019) focused on the importance of education and being literate to children. We were very interested in Andresen and Fegter’s (2011) study about children who lived in poverty in Germany and addressed how they conceived of justice and a good life. The results of their mixed-methods research revealed the importance of family, welfare services, friends and physical closeness, non-violence, school and learning, health care, pets, play and vacations. Studies by Dominguez Serrano et al. (2019) used a similar approach working with children in Spain who took part in Children Municipal Councils. The authors and the children discussed and validated a list of capabilities relevant to the well-being of children in southern European regions. In their conclusions, children demonstrated a multidimensional understanding of well-being and perceived a change in the relevance of capabilities throughout the life process. The researchers observed that the capabilities children deemed most relevant for themselves to have a good life (education and affectivity, emotions and love) did not exactly coincide with those children thought adults needed the most, although variations by sex and age were observed.

In parallel, there is a growing interest in the subjective dimensions of child well-being. We identified several articles using a quantitative approach based on the analysis of the data generated by the ISCWeB. For example, Steckermeier (2019) underlines how explicitly considering children's agency with respect to their safety contributes to a better understanding of their subjective well-being. On the other hand, López Reyes (2019) analyses the interactions between hypothetical individual-level predictors and country-level moderators. The results of this study are generally consistent with the vision of well-being as a psychological construct that changes with the material and cultural environment of children.

Other studies address the possibilities of developing an integrated view of well-being using objective and subjective measures collected through surveys (Domínguez-Serrano et al., 2019), mix-method (Babb et al., 2017) or creative methods (Kellock, 2020).

Intersectionalities, Identities and Inequalities

Although only one of the papers explicitly includes the notion of "intersectionality" (see Cabezas & Schweiger, 2016), many of them explore the ways in which the intersection of age with gender or other socio-cultural and economic differences shape children’s lives and identities. Some texts specifically address gender issues. Cabezas and Schweiger (2016) focus on girls (girlhood) and bodily integrity, the right to be free from physical harm and harassment, and experience freedom and security concerning the body. They state that the capability approach offers an ethical framework that allows for the assessment of girls' well-being and well-becoming concerning the potential and often subtle threats they face. Using a quantitative approach, Addabbo et al. (2014) conducted a gender analysis of two capabilities, the capability to sense, imagine and think and the capability to play in Italian boys and girls. Their article pays special attention to the effects of the interaction between the child and their father, mother or caregiver, showing how the joint activities carried out vary according to the sex of the child and the region where they live. On the other hand, D'Agostino et al. (2018) examine gender disparities in children's well-being by considering seven capabilities and the intersection of family structures in four southern European countries: Portugal, Italy, Greece and Spain. The results indicate that gender has an effect on well-being and the need for gender-specific and dimensional policies to improve children's well-being.

Another (reduced) set of articles focusing on Australia (Mishra et al., 2018), New Zealand (Cram, 2019) and Mexico (Veladez-Martínez, 2016) include ethnicity in their analysis, while this issue is overseen in most of the other regions. For example, the experience of indigenous Australian children is compared with that of the general population, concluding that indigenous children suffer a higher rate of disadvantage that increases with age and is particularly severe in terms of "bullying" and "bodyweight" (Mishra et al., 2018). Other studies focus on the well-being of Mäori children and emphasise how important it is that the development of indicator sets in specific contexts include these groups as key participants so that it reflects Mäori understandings and serves Mäori interests (Cram, 2019).

Some research focuses specifically on the experiences of children with disabilities. Terzi (2014) highlights how focusing on educational capability equality while placing the well-being and agency of children with disability at the core of questions of fair educational provision implies a broader reconsideration of pedagogy, curricula and policy.

Discussion and Conclusions

The growing interest in the field of child well-being has contributed to the great diversity and dispersion in the existing literature. Hence, this article constitutes an innovative and, in our opinion, helpful work for those who aim to approach this topic, particularly with a focus on capabilities. Since we consider the CA to be a fundamental tool for studying childhood and children's lives, we aimed to conduct a systematic review of the existing literature regarding the application of this approach to children, with particular attention to child well-being. Therefore, we aim to contribute to identifying and filling the existing gaps in research on child well-being from this approach. In doing so, we have focused on the geographical areas, the spaces, the methodologies, the well-being and well-becoming dimensions, and the intersectionalities addressed by a selection of 37 documents that emerged from a systematic review.

One limitation of this methodology is directly related to the particular methodology applied. Systematic search methodologies can sometimes leave out documents that are relevant to the field in question. This issue was the subject of debates within our research team and again arose during the review process of the article. One example of a document that was left out of the sample is Pelenc (2017). This exclusion was due to the fact that our search was constructed around the notion of childhood (we includes “child*”, “boy*” and “girl*”) but not specifically around adolescence (*teenager or *adolescen) that, sometimes, is more connected to youth studies.

Even so, our analysis shows that capabilitarian perspectives of child well-being help acknowledge the objective and subjective dimensions of well-being from both a structural and an individual perspective, expanding the notion beyond material issues. Moreover, this approach favours considering specific groups' realities through various inequality axes, gender, among others, and addressing how children own understand the "good life”. As a result, an important set of papers consider children as the experts in their lives and use, for example, children’s self-reports as the basis for assessing their well-being.

However, the results reflect gaps in empirical research in the Global South and the predominance of quantitative approaches. In fact, another facet that needs to be further developed is the design and application of research instruments that are not dominated by a Western ideal of childhood and are considered universally valid (Liebel, 2005 in Wilmes & Andresen, 2015). In this sense, a more profound and explicit commitment to intersectional perspectives may favour new and more complex understandings of child well-being from the CA.

In addition to that, despite the significant advances that have taken place in recent years, the debates on whether the CA is fully applicable to children remain open. It is also necessary to continue exploring the themes of autonomy, agency and self-determination as they relate to children. Should children be provided with extensive opportunity freedom in the first stage, or this process freedom should only be granted as they eventually become adults? In this debate, Bovin and Stoecklin (2014) warn us against extreme positions that do not help move forward in the discussion. At this point, the concept of "evolving capabilities" proposed by Biggeri et al. (2011) is much more insightful as probably “the most appropriate combination between opportunity and process freedom cannot follow on the divide between children and adults, but needs to take account of this dynamic process.” (Bovin & Stoecklin, 2014, p.4).

These debates do not hinder the approach's potential to address children's well-being. On the contrary, we believe they contribute to equipping us in the face of new challenges such as the ones posed by, for example, the Covid19 pandemic context. The CA helps us identify and understand children’s goals and the resources, contexts and actions that might make achieving these goals possible (Thomas & Stoecklin, 2018). This complements the (child) rights-based perspectives by arguing that rights can only become effective if children are situated in a position where they can actively and genuinely enact them. Indeed, a large part of the analysed documents commented on their findings' political implications and proposed a series of recommendations for designing and developing policies and programs promoting child well-being. The CA can be very enlightening in all these areas, and we are confident that research in this field will continue to yield fruitful contributions in the coming years.