This study investigated the evolving relations between peer victimization and social/emotional difficulties in middle to late childhood. Peer assessments of peer victimization and social/emotional difficulties (aggressive behavior, social withdrawal, and emotional vulnerability) were collected over 4 years for 1,035 children attending Grades 3-6 and were analyzed via cross-lagged panels and trajectory analyses. All dimensions were highly stable and significantly related initially. Peer victimization became progressively less related to aggression and increasingly associated with withdrawal. Bidirectional contributions over 1-year periods were found between withdrawal and emotional vulnerability and victimization. Trajectory analyses revealed heterogeneity in peer victimization patterns, with a small group of children (4.5%) being extremely victimized and with another group (10%), less severely, but increasingly victimized over time. Compared to nonvictimized children, these children were generally more emotional and became less aggressive but more socially withdrawn over time. These small behavioral changes were not associated with decreases in victimization. (Contains 5 figures and 1 table.)