The transition to middle school places many adolescents at risk for negative adjustment, especially poor and underserved ethnic minority students. In this cross-sectional study, I explored the role of student-perceived mismatch in the transition to a school with an early-college model, using a sample of predominantly African American and Latino students from low-income backgrounds (N = 154). Mismatch in developmental (connection and autonomy), academic (expectations and involvement), and racial-ethnic (in-group connectedness, embedded achievement, and awareness of racism) socialization across both the school and home environments was examined. Predictive relationships between perceived mismatch and both engagement and achievement were tested. In addition, comparisons were made between the role of perceived mismatch versus perceived real environment in the prediction of student outcomes. Across all three domains of socialization, students perceived significantly greater mismatch between their real and ideal environments at school than at home. Student-perceived mismatch and engagement did not significantly vary by student or school demographic characteristics, but student achievement was higher for those students beyond the transition year. Only student-perceived mismatch at home significantly predicted students' engagement and beyond this, perceptions of higher connection to and autonomy from teachers as well as lower academic involvement significantly predicted greater student engagement. For students beyond the transition year, achievement gains were greater and linked to perceptions of more home-school match, but here, perception of real school environment did not significantly predict math achievement gains. Implications for underprepared students' adjustment during the transition to a secondary school with an early-college model are discussed.