The effectiveness of training parents in behavior modification techniques to alter inappropriately aggressive behavior of boys aged 6-14 was evaluated. Six boys designated a treatment group were matched on the bases of age, socioeconomic status, and mean and variance of inappropriate aggressive behavior with a control group. Parents of treatment group boys were taught social learning procedures for five weeks. Parents of the control group boys received not training. Observers recorded the rates of deviant behaviors in family interactions within the home for both groups. It was found that the parents’ application of the training resulted in a significant decrease in the rate of deviant behavior of children in this group. Children in the control group showed an increase of inappropriate behavior during the comparable period.