Classroom behavior management interventions have been used successfully with drug prevention programs to prevent subsequent antisocial behavior and substance use among youth. This article presents results from implementation of the All Stars Challenge, a classroom-based behavior management component to a drug prevention program for fifth graders. Risk ratings for shyness and lack of awareness of social norms among high-risk students who received the All Stars Challenge were reduced compared with fifth graders who did not receive the intervention. In contrast, physical and social aggressivity among low-risk students who received the program increased when compared to similar control students. (Contains 4 tables.)