This special issue of the journal focuses on a phenomenon that has long been evident in East Asia—especially Korea, Japan, Hong Kong and Taiwan—and in recent decades has become very prominent elsewhere. The phenomenon is widely known as shadow education, meaning a form of education that mimics or shadows the mainstream regular school system but which exists beyond its boundaries. The majority of papers are based on presentations during a 2008 international conference in Seoul National University. The papers were subject to rigorous blind review, which resulted in acceptance (and improvement) of some and rejection of others. To these contributions were added further papers following a general call. The result is a wide-ranging set of papers which significantly advances understanding on the theme.

Part of the value of the set of papers lies in the exploration of the concept of shadow education. In general, shadow education is here taken to cover fee-paying supplementary tutoring in academic subjects for pupils who are already learning those subjects in mainstream schools. However, different writers have used the term in slightly differing ways. Strong commonality is evident in the papers collected here, but divergence in other parts of the literature has been among the challenges for international comparison.

A related challenge has been that even when researchers have a clear understanding in their minds, they may find it difficult to devise instruments that accurately measure the scale, orientation, intensity and quality of shadow education. Some of these challenges are explored in Bray’s initial paper about methodology, which includes focus on the Trends in International Mathematics and Science Study (TIMSS) organized by the International Association for the Evaluation of Educational Achievement (IEA), and on the Programme for International Student Assessment (PISA) of the Organisation for Economic Co-operation and Development (OECD). The TIMSS and PISA instruments were not designed specifically to measure shadow education and have proven insufficiently sharp in their approaches. Research on shadow education is in its infancy and needs continuing attention to matters of methodology as well as to interpretation of findings.

Other papers focus on the spread of shadow education and on the forms that it has taken in different cultures. This requires attention to demand as well as supply. The factors underlying demand are very different in urban and rural areas, and in rich and poor societies. They may also reflect the structure of education systems and the role of the government in discouraging or promoting shadow education. Factors determining supply include the structure of the economy and the regulations that govern the work of teachers. In some societies, teachers are forbidden to provide private tutoring for their own pupils, and most tutoring is therefore undertaken either by other teachers or by specialist institutions. In other societies, teachers are permitted to tutor their own pupils. This can have beneficial dimensions insofar as the teachers already know the pupils well, but it can also raise problems of ethics.

Dawson’s paper is among the ones with an explicit comparative focus. Addressing the phenomenon in Japan, Korea and Cambodia, he shows that much can be learned through comparative analysis about the different types of shadow education and the forces that shape it. Similarities between Korea and Japan are stronger than between either of these countries and Cambodia. Japanese juku have had a major role in maintaining social inequalities, but until recently have largely been ignored by the government education authorities. Perhaps, though, the models of juku in Japan and their counterpart hagwons in Korea are less problematic than the dominant form of tutoring in Cambodia in which classroom teachers provide much private tutoring to the pupils for whom those teachers already have responsibility in the regular schools. In Japan and Korea, the existence of tutoring may reflect corruption of the education system in the sense of a malfunctioning, just as a malfunctioning computer disc might be considered corrupted; but in Cambodia, the corruption also has a moral element, particularly if teachers are tempted to teach only part of the curriculum during the normal school day in order to expand demand for their services from the same pupils after school hours.

At the same time, it is important to recognize many types and qualities of shadow education even within individual countries. Dawson notes a range of types of juku, and Dierkes goes further. His paper reports on the backgrounds and modes of operation of owner-operators of small juku in Japan. His research based on interviews and classroom observations provides many instructive insights.

Several papers also note that the shadow system is evolving in significant ways over time. Mori and Baker ask why shadow education has expanded, and what it means for the future of education in postmodern society. Like Dierkes, Mori and Baker mainly focus on Japan. On the basis of analysis of historical patterns and more recent developments, they suggest that shadow education follows the institutional logic of formal education. They predict that shadow education will be increasingly incorporated into the broader culture of education both in Japan and elsewhere.

Kwok focuses on China, but also has a comparative focus insofar as he notes instructive contrasts between Hong Kong, Macao and a range of cities, towns and provinces in mainland China. Private tutoring has long been an obvious phenomenon in Hong Kong, but has recently expanded in scope and competitiveness. Thirty years ago, under the strict communist regime, there was practically no such tutoring in China, but it has expanded dramatically with the advent of the market economy.

At the same time, technology is greatly changing many dimensions of teaching and learning. Ventura and Jang show ways in which the internet is permitting tutoring across borders, cultures and time zones. It is a remarkable form of globalization which is significantly shaping educational experiences in certain societies. With this lens, one may see that tutoring maintains and exacerbates social inequalities. In all contexts, prosperous families are able to access greater quantities and better qualities of tutoring than can lower-income families. The addition of the technological dimensions and the social connections necessary to make use of them further exacerbate inequalities.

A rather different model of research is provided by Lee, whose focus is on university students’ pre-university exposure to extracurricular English instruction in tutorial and private institutions in Korea and abroad. Lee thus addresses the question whether and how much tutoring can shape learning outcomes. Further work is needed on this theme at a range of levels and in a range of settings. As one might expect, in general the literature shows that the extent of learning is highly dependent on the motivations and personal characteristics of the tutors and tutees. It cannot be assumed that supplementary tutoring is always a good investment for enhancing achievement.

Byun also focuses on Korea. He is especially concerned with the high school equalization policy, which was designed to reduce the demand for private tutoring but in practice had little effect on the financial burden especially for lower income countries. This experience is very instructive for governments in other countries as well as in Korea. Lee, Lee and Jang provide a related but broader lens. They trace the history of policy interventions in Korea, highlighting what they mostly see as failed attempts to control the shadow education system and suggesting directions for the next cycle of policy responses.

In part because of the location of the original conference, but also because of the significance of the theme in that country, it will be evident that a notable proportion of the papers focus on Korea. Private tutoring has been a topic of public debate and policy intervention for several decades in Korea. Partly for this reason, Korean researchers are among the world’s leaders. The quantity and quality of research on the topic in Korea stands out internationally and provides models from which researchers in other countries can learn.

Taken together, this collection of papers represents a significant advance in this infant field of research. We hope that they will stimulate further advances to enhance the rigor of analysis and strengthen the insights that can be gained from cross-national and intra-national comparisons.