The effectiveness of a parenting program with 394 Head Start mothers was examined. Nine Head Start centers were randomly assigned to either an experimental condition in which parents, teachers, and family service workers participated in the intervention or a control condition in which the regular Head Start program was offered. Mothers in the intervention group were observed at home to have significantly fewer critical remarks and commands, to use less harsh discipline, and to be more positive and competent in their parenting when compared with control mothers. Teachers reported that intervention mothers were more involved in their children's education and that their children were more socially competent. Intervention children were observed to exhibit significantly fewer conduct problems, less noncompliance, less negative affect, and more positive affect than control children. One year later most of the improvements were maintained.