This study provides evidence of the effectiveness of behaviorally based parenting skills classes provided by carefully trained and supervised group leaders who were not mental health clinicians. A program for parents of at-risk middle school students was evaluated in a randomized controlled trial in 8 small Oregon communities. Parents (N = 303) were randomly assigned to immediate treatment or a wait-list condition. Data were analyzed using latent growth modeling. Participation in the program led to significant improvements in problem-solving interactions as indicated by parent reports and a Taped Situations Test. Parents' over-reactivity and laxness toward their children's behavior were reduced and their feelings toward their children improved significantly as a function of treatment. Parent-reported child antisocial behavior was also reduced.