Objective: Examine after-school activity patterns, eating behaviors, and social environment of overweight and normal weight middle school students. Design: Eating and physical activity behaviors of 141 students, ages 10-14, were monitored. Students completed a diary documenting type of activity, location, adult supervision, accompanying participants, and eating habits from 3:00 pm-12:00 am. Setting: Three middle schools, grades 6-8. Main Outcome Measures: Body mass index, estimated energy expenditure, eating behavior, active time, sedentary time, supervised time. Analysis: t tests, ANOVA, chi-square, correlation coefficients. Significance set at P less than 0.05. Results: Children spent 76% of time sedentary, and 85% of sedentary time was under adult supervision (r = 0.76). Active time related to time with friends (r = 0.64) and family (r = 0.46). Children spent 40% of eating time consuming unhealthful food, and adults supervised 86% of children's eating. Overweight and normal weight children were similarly active (335 [plus or minus] 156 vs 373 [plus or minus] 194 counts per minute). Overweight girls spent more eating time (77%) eating healthfully than overweight boys (57%). Conclusions and Implications: Children should be given access to healthful food and encouraged to eat healthfully when alone and with friends. Adults should be more physically engaged with children. Children should be encouraged to eat under adult supervision and with their families. (Contains 2 figures and 3 tables.)