BackgroundThe current evidence for child maltreatment and domestic violence and abuse interventions is limited by the diversity of outcomes evaluated and the variety of measures used. The result is studies that are difficult to compare and lack focus on outcomes reflecting service user or provider priorities.ObjectiveTo develop core outcome sets (COS) for evaluations of child and family-focused interventions for: i) child maltreatment (CM); and ii) domestic violence and abuse (DVA).DesignWe conducted a two-stage consensus process. Stage one: A longlist of candidate outcomes across CM and DVA was developed through rapid systematic reviews of intervention studies, qualitative and grey literature; stakeholder workshops; survivor interviews. Stage two: Three-panel, three round e-Delphi surveys for CM and DVA with consensus meetings to agree the final COSs.Participants287 stakeholders participated in at least one stage of the process (i.e. either CM or DVA COS development): initial workshops (n=76), two e-Delphi surveys (n=168) and consensus meetings (n=43). Stakeholders included survivors, practitioners, service commissioners, policymakers, and researchers.ResultsStage one identified 335 outcomes categorised into nine areas and 39 domains. Following stage two, the final five outcomes included in the CM-COS were: child emotional health and wellbeing; child’s trusted relationships; feelings of safety; child abuse and neglect; service harms. The final five outcomes in the DVA-COS were: child emotional health and wellbeing; caregiver emotional health and wellbeing; family relationships; freedom to go about daily life; feelings of safety.ConclusionsWe developed two core outcome sets for CM and DVA with two common outcomes (child emotional health and wellbeing; feelings of safety). The COSs reflect shared priorities amongst service users, providers, and researchers. Use of these COSs across trials and service evaluations for children and families affected by CM and DVA will make outcome selection more consistent and help harmonise research and practice.