This study reports the results of a pragmatic effectiveness-implementation hybrid trial of the Family Check-Up (FCU) conducted in three community mental health agencies with 40 participating therapists. Seventy-one families with children between 5 and 17 years of age participated. Intervention fidelity and level of adoption were acceptable; families reported high service satisfaction; and therapists reported high acceptability. Families in the FCU condition experienced significantly reduced youth conduct problems in comparison to usual care and completion of the FCU resulted in larger effects. This study provides promising evidence that implementing the FCU in community mental health agencies has the potential to improve youth behavior outcomes.