This paper reports on the first phase of a project funded by the UK Economic and Social Research Council concerned with promoting interpersonal awareness and prosocial behaviour through classroom peer interaction activities. This intervention study involves more than 400 Scottish school children aged approximately 9 years. Peer nomination techniques were used to identify children whose behaviour could be characterised as (a) prosocial; (b) antisocial; (c) victim and (d) neutral. Samples of children were assessed individually using a series of instruments measuring empathy, social problem-solving, socio-moral reasoning and social perspective- taking. The paper examines the issues arising out of the intercorrelations among these measures and also considers the emerging characteristics of male and female prosocial children, bullies and victims. Also discussed is the design of a series of structured peer interaction tasks, focussing upon interpersonal awareness and problem solving which have been introduced into classrooms and the strategies adopted to address the methodological problems associated with school intervention studies in the affective domain.