This study assessed the role of social support in the outcome of child management training (CMT) for single parents of conduct problem children and assessed the impact of adjunctive ally support training (AST) on treatment outcome. Single parents (N = 22) with a child diagnosed as oppositional or conduct-disordered received CMT or CMT plus AST. Each group received the same 6-week parent training program and the AST group received an extra social support intervention. Measures of parent behavior, child deviance, social support (SS), and parental depression were obtained at pre- and posttreatment and at 6-month follow-up. Both groups improved, and changes maintained at follow-up. AST produced no extra gains. Responders from either group were more likely than nonresponders to report high levels of SS from friends. Results emphasize the importance of SS and the difficulty of incorporating changes in SS into treatment programs.