The effects of group parent training on parent behavior, and on the behavior of 45 children with attention-deficit hyperactivity disorder and defiant aggressive behavior, were evaluated with a pre-post design. Parent training included didactics on the features and etiology of ADHD and its relationship to defiant/aggressive behavior, as well as parenting skills that adhered to parameters established in the Behavior Management Flow Chart (BMFC). The logic that guided the construction of the program and the unique aspects in the form and content of the parent training are identified. Outcome data show that training reduced childrens' hyperactive, defiant, and aggressive behavior, improved parenting behavior, and reduced parent stress. These data are comparable to previous outcome research evaluating the efficacy of parent training with the BMFC. The advantages of programs that are efficacious in group settings are discussed.