This article presents u model of the interrelationships between students 'family, peer, and school worlds, and, in particular, how meanings and understandings derived from these worlds combine to affect students' engagement with schools and learning. In addition, the model focuses attention on students' perceptions of boundaries between worlds and adaptation strategies they employ to move from one context to another. W e use a typology to illustrate four patterns we have found among 54 students in four desegregated high schools as they move across settings: (1) Congruent WorldslSmooth Transitions; (2) Different WorldslBoundary Crossings Managed; (3) Different WorldslBoundary Crossings Hazardous; (4) Borders ImpenetrablelBoundary Crossings Insurmountable. Unlike most other approaches, the model we present is generic. It transcends ethnic, achievement, and gender categories to consider multiple worlds, boundary crossings, and adaptation for all students. PSYCHOISO-TIONSHIPS ClAL I'ROCESSES, ADOLESCENTS, HOMEISCHOOLIPEER RELA-Patricia Phelan is Senior Research Scholar, Center for the Research on the Context of Secondary School Teaching, School of Education, Stanford University. Ann Locke Davidson and Hanh Thanh Cao are graduate students, School of Education, Stanford University. 224 Phelan/Davidson/Cao Students' Multiple Worlds 225This article describes the Students' Multiple Worlds Study and the framework that has evolved during the first year of the investigation. Our purpose is twofold: first, to describe family, school, and peer worlds, the interrelationships between them, and, in particular, how meanings and understandings combine to affect students' engagement with learning; second, to understand students' perceptions of boundaries between worlds and adaptation strategies they employ as they move from one context to another. We use the term world to mean cultural knowledge and behavior found within the boundaries of students' families, peer groups, and schools; we presume that each world contains values and beliefs, expectations, actions, and emotional responses familiar to insiders. We use the terms social setting, arena, and context to refer to places and events within which individuals act and interact. Students employ cultural knowledge acquired from their family, peer, and school worlds in social settings and contexts. Social settings and contexts may be found within the bounds of any one world (e.g., a student having dinner with family members), or they may include actors from various worlds (e.g., students interacting with friends in classrooms, or friends visiting in each other's homes). In the latter case, people in the same social setting may or may not share the same cultural knowledge acquired from the constellation of their individual worlds2 The terms boundaries and borders refer to real or perceived lines or barriers between worlds.Prior research generally has focused on families, peers, and schools as distinct entities. We know that any one can affect powerfully the direction in which adolesc...