Issues of access, social exclusion and widening participation dominate educational policy agendas and are a shared global challenge. Participation in higher education and adult lifelong learning activities can be a life-changing experience that opens up new opportunities. However, access remains unequal. People from lower socio-economic backgrounds, those living in the most deprived areas and people from minority ethnic groups are underrepresented. In this book, we focus on how we can move the field of widening participation forward, paying specific attention to the theories and methods we can use to better understand and tackle the problem of underrepresented groups in post-compulsory education, and how individuals and institutions can be supported. We argue that in order to make sense of these issues, it is important to engage in both the findings of widening participation research and the theoretical foundations which underpin them. This way, alternative perspectives on the widening participation agenda and emerging research and policy can be explored from alternative perspectives. This book was originally published as a special issue of Studies in Continuing Education.