Relations of regulation and emotionality to social functioning were examined for 77 children followed from early to middle school age. Parents and teachers reported on children's social behavior, emotionality, and regulation, and children engaged in analogue peer conflict situations (i.e., with puppets). High-quality social functioning was predicted by high regulation and low levels of nonconstructive coping, negative emotionality, and general emotional intensity. Prediction often was obtained across reporters and time, although prediction was strongest within context (home versus school). Moreover, measures of regulation and emotionality frequently contributed unique variance to the prediction of social functioning. Contemporaneous correlations at age 8-10 were similar to those obtained at age 6-8, and prediction of later social functioning from emotionality and regulation at age 4-6 was similar at ages 6-8 and 8-10.