Person × Environment mismatch theory has been applied to understanding how the classroom social ecology moderates associations between peer victimization and socioemotional well-being. In 2004, Bellmore et al. applied this theory to the ethnic composition and social climate of the classroom. The current study tested whether their findings replicate with a slightly younger, rural sample from the Southeastern United States, whether associations held longitudinally, and whether child ethnicity moderated effects. Participants were 4th-grade and 5th-grade students from 13 elementary schools (N = 1,448; M[subscript age] = 10.13 years; 701 girls; 37.9% Black, 4.40% Latina/o, 57.7% White). Measures included peer-reports of peer victimization, teacher-reports of loneliness, social withdrawal, and anxiety, and self-reports of prosocial peer treatment. Classroom social disorder was assessed using teacher-reports of aggressive behavior and peer victimization. Evidence that having a large percentage of same-ethnicity peers amplifies peer victimization-adjustment linkages was limited. Although the exact nature of identified interactive effects somewhat varied from Bellmore et al., findings similarly underscored the benefits of low social disorder and ethnically diverse classrooms. Together, these findings point to a need to understand the proximal sociostructural impact of ecological factors when studying the consequences of peer victimization.