The special issue aims to develop a greater understanding of the relationship between social cognitive development in adolescence and social behaviour, to discuss the mediating effects of other aspects of development in adolescence such as the parallel emergence of ideas concerning personal identity, patterns of relationship development within or outside the family, and to examine new approaches to the study of social development in adolescence. Finally it considers the problems (practical, methodological and ethical) associated with intervention in adolescence and how the approach(es) which are adopted may be guided by our understanding of young people's social cognitive development.