This book highlights one school district's attempt to desegregate its schools according to socioeconomic status, focusing on a study of 10 fourth-grade classrooms. The study uncovered the ways that teachers' leadership styles, tasks, and reward structures affected students' peer relations. The 9 chapters focus on: (1) "Socioeconomic Desegregation and Community Politics" (the community of LaCrosse and the desegregation plan); (2) "Desegregation, Integration, and the Gulf That Can Lie Between Them" (desegregation and integration and classroom social organization); (3) "Places and Cases: The Toolbox Opened" (selection of 5 schools and 10 classrooms and data sources); (4) "Stepping Inside Ten Classrooms" (descriptive framework for activity and reward structure and the classrooms); (5) "A First Look at Peer Relations: Hierarchy and Egalitarianism" (predicting the shape of peer relations and distributions of workmate nominations); (6) "More on Peer Relations: Cohesive Subgroups" (e.g., two classrooms compared, subgroup membership, and egalitarian versus hierarchy); (7) "A Further Examination of Workmates and Playmates" (the models and findings); (8) "The Roots of Belonging and Participation" (location and focusing on students); and (9) "Implications for Educational Research and Practice" (revisiting five conditions for improved intergroup relations). An appendix presents the Student Sociometric Survey Instrument. (Contains references.) (SM)