Non-classroom settings are often the most violence-prone areas within a school. This study investigated the impact of an interdependent group contingency on the disruptive behaviors of students in grades K-6 in an urban school cafeteria. Nine female noontime aides and National School and Community Corps staff members implemented the Lunchroom Behavior Game (LBG), a modification of the Good Behavior Game (Barrish, Saunders, & Wolf, 1969), within a multiple-baseline design across three lunch periods. Results showed a decrease in the level of disruptive behaviors following the implementation of the LBG in each lunch period and a decreasing trend for two of the three lunch periods. Discussion focuses on the use of the LBG in preventing antisocial behavior and role expansion for school psychologists interested in promoting school-based prevention strategies. (Contains 1 figure.)