A multiple family group (MFG) is a family-centered, group delivered, evidence-informed, manualized intervention that targets the most common reason for referral to publicly funded clinics: youth oppositional defiant and conduct disorders. This study will employ a mixed methods Type II effectiveness-implementation hybrid research design.In collaboration with the NYS Office of Mental Health (OMH), this longitudinal study will be conducted across the NYC OMH licensed child behavioral health clinic system (n=134). The investigators will use mixed methods, and involve 268 providers and 2,688 adult caregivers of youth (7 to 11 years).