This study evaluated the effects of a functional assessment in-service training and mental health consultation with Head Start teachers on the aggressive-disruptive behavior of preschool children. Subjects included eight Head Start children exhibiting high rates of aggressive-disruptive behavior and eight teachers who had difficulty managing problem behaviors and little knowledge of functional assessment of problem behavior. All eight teacher-child dyads were observed between three to nine times to collect data on target behaviors. Four of the eight participating teachers attended the functional assessment in-service, during which time a behavior support plan was developed. During implementation of the behavior support plan, trained observers collected data for 30 minutes three times a week, until three to nine data points were obtained. Following this phase, all eight teacher-child pairs were observed by coaches who collected data for 30 minutes, 3 times a week and met with each teacher for about 20 minutes to provide feedback.