This study used a trichotomous achievement goal model to explore and describe what actually happened in terms of students' achievement goals and disruptive behaviors in an after-school physical activity program. Participants included 158 students in grades 3-6. They completed questionnaires assessing their achievement goals and disruptive behaviors. Nine of the participants were also selected and observed for disruptive behaviors. Students reported higher scores on the mastery goal than they did on the performance-approach and performance-avoidance goals. The mastery goal was negatively related to students' self-reported low engagement, whereas the performance-approach and performance-avoidance goals were positively related to students' self-reported disruptive behaviors. Overall, findings of the study provide empirical support for the trichotomous achievement goal model as a viable theoretical framework in the study of students' disruptive behaviors in after-school physical activity settings. (Contains 3 tables.)