BackgroundFamily group decision-making (FGDM) is a structured decision-making process, aiming to shift the balance of power from professional towards the person in need and their family. It differentiates from other family-centred meetings by the presence of three key elements: (1) plan with actions/goals, (2) family driven, (3) three phases of meetings gradually increasing empowerment. FGDM studies are increasing in different settings in adult healthcare/welfare, although effectiveness is unknown at this date.Objectives(1) to systematically review the presence of the three FGDM key elements in family-centred interventions in adult care and welfare, (2) to evaluate the effectiveness of FGDM interventions.DesignSystematic review.Data sources and eligibility criteriaA total of 14 relevant electronic databases and 1 academic search machine were searched until February 2018. First, family-centred studies were selected with controlled trial designs in adult healthcare/welfare. Second, interventions were categorised as FGDM if all three key elements were present.Data extraction and synthesisStudies were examined concerning their (1) characteristics (2) quality/level of evidence (3) presence of FGDM key elements and (4) results.ResultsSix articles from three studies on family-centred interventions were selected from a total of 1680 articles. All were of low quality. One study (two articles) met all criteria for an FGDM intervention, describing the efficacy of family group conferences among social welfare recipients on mental health outcomes. Although the intervention group showed significantly better outcomes after 16–23 weeks; no differences were seen at the 1-year follow-up.ConclusionsControlled studies of both family-centred interventions and FGDM are still low in quantity and quality. No conclusions on FGDM effectiveness can be drawn. Further high-quality intervention studies are required to evaluate the impact of FGDM on adults in need, including their families; as well as evaluation research detecting possible barriers and facilitators influencing FGDM implementation.PROSPERO registration numberCRD42017077585.