Relatively few functional assessment and intervention studies have been conducted in preschool classrooms with children of typical development who engage in high incidence problem behaviors. Moreover, limited studies have used functional assessment procedures with the class as the unit of analysis. This study included functional analyses and a function-based differential reinforcement procedure for 2 preschool classrooms referred for behavioral consultation services because multiple students were engaging in disruptive behavior. Results indicated that function-based differential reinforcement interventions resulted in reductions in children's disruptive behavior and teachers rated assessment and intervention procedures as acceptable. The authors discuss the results in terms of functional assessment and function-based intervention research and practice in preschool classrooms. (Contains 2 figures.)