The current study investigated the effectiveness of a short-term, cognitive behavioral program for 106 primary school-aged children referred with externalizing behavior problems and their parents, compared with 39 children and their parents on a waiting-list to be treated. Exploring Together' comprised a children's group (anger management, problem-solving and social skills training), a parents' group (parenting skills training and dealing with parents' own issues), and a combined children's and parents' group (to target parent-child interactions). The program reduced children's behavior problems and improved their social skills at home. Changes in children's behaviors and social skills at home were generally maintained at 6- and 12-month follow-up. Implications of the findings for improving interventions for childhood externalizing behavior problems are discussed.