This book describes a British project which used cooperative group work as a curriculum approach to help reduce children's social difficulties and encourage cooperation and friendship across such barriers as race, sex, or disability. The book consists of eight chapters. Chapter 1 provides an overview of research findings and theory related to peer acceptance, friendships, and bully-victim problems in junior school (elementary) classrooms. Chapter 2 discusses theory and research related to ethnicity, relationships, and attitudes in children. Chapter 3 concentrates on cooperative group work in primary schools. Chapter 4 provides the background to the project, including project design. Chapter 5 describes inservice training and support for teachers in the values of cooperation that the teachers would promote in their classes. Chapter 6 discusses the effects of cooperative group work on children's social relationships. Chapter 7 provides a close look at individual differences and case studies of children taking part in the program. Chapter 8 provides conclusions and recommendations concerning: (1) the two primary dimensions of social relationships--affiliation and power; (2) the meaning of cooperation; (3) the potential of cooperative group work in the classroom; (4) the successes and failures of the project, and an analysis of why failures occurred; and (5) a discussion of the future of cooperative group work for improving social relationships. An index is included. Contains 169 references. (DR)