Background: Children in foster family care face elevated risks in mental and physical health, social functioning, and placement stability. Various interventions aim to strengthen foster family care, yet the evidence base remains unclear.

Objective: This systematic review synthesizes evidence on the effects of interventions intended to strengthen foster family care on children’s well-being and functioning, placement stability, and foster caregivers’ mental health and parenting skills.

Methods: A comprehensive search of international databases identified controlled studies evaluating interventions delivered before or during foster family placements. Interventions were grouped into five categories based on primary focus. Risk of bias and certainty of evidence were assessed using established criteria. Meta- analyses were conducted where appropriate.

Results: 29 studies covering 22 interventions were included. Attachment-focused parenting programs reduced attachment insecurity among children in foster family care, although the certainty of evidence was low. Behavior-focused parenting programs reduced externalizing symptoms, and education-focused tutoring and mentoring programs improved reading skills, but the evidence was limited. For treatment foster care for younger children and other psychosocial interventions, evidence was insufficient to draw conclusions. Outcomes such as placement stability and children’s physical health were rarely studied. Effects on foster caregivers’ parenting skills and mental health could not be determined.

Conclusions: The evidence base on interventions to strengthen foster family care is limited and characterized by substantial knowledge gaps. More rigorous evaluations are needed to inform child welfare practice and policy.