The links between children's externalizing behaviors and two characteristics of children's social interactions within the classroom, namely, peer social preference and received support from the teacher, were studied in 570 children followed from their 2nd- to 3rd-grade years of elementary school. Data consisted of peer and teacher reports of externalizing behavior, sociometric "liked most" and "liked least" nominations, and teacher rated support. Results showed consistent paths from externalizing behavior to (low) peer social preference. Peer social preference, in turn, predicted decreases in externalizing behavior, even after taking teacher support into account. Teacher support was not consistently linked to the development of externalizing behavior across time. However, an indirect path from externalizing behavior, via (low) peer social preference, to lower levels of teacher support was found. These results were similar for girls and boys. (Contains 1 footnote, 2 tables, and 2 figures.)