This longitudinal study had three objectives: (a) to identify different profiles of second-year middle school students (Grade 8) in terms of academic, emotional, and social adjustment; (b) to test the contribution of worries at the end of Grade 6 to distinguish these profiles; and (c) to examine the moderating effect of mastery (MG) and performance goal (PG) structures in language arts class (Grade 7). A total of 342 mother-adolescent dyads participated in the study. Cluster analyses revealed three adjustment profiles: a well-adjusted group (WA), a socioemotionally adjusted group (SEA), and a socially adjusted group (SA). Hierarchical multinomial regression analyses showed that students who expressed worries had a lower probability of being in the WA. However, students who had a teacher who emphasized MG had a greater probability of being in the WA. Finally, worries about peers and teachers lowered the probability of being in the WA for students exposed to PG. Results are discussed in light of their implications for the literature on student adjustment, the elementary-to-middle school transition, and classroom goal structure. (Contains 2 tables and 1 figure.)