The child welfare system strives to balance protecting the safety and well-being of abused and neglected children with preserving families whenever possible. When children must be removed from their homes and placed in foster care, family reunification is the preferred child welfare strategy. Unfortunately, not all reunifications are successful, and a significant number of children re-enter foster care each year. Foster care re-entry represents a failure of permanency that has potentially serious negative effects on children. Thus the child welfare system must work to reduce and prevent re-entry to foster care. This literature review examines the research on foster care re-entry, including risk and correlates of foster care re-entry and resilience and correlates of successful reunification to understand factors related to re-entry that can be used to design assessment tools and interventions. The article then describes the effects of child welfare services and program models on reducing foster care re-entry, and concludes with a discussion of the implications of the findings for child welfare practice and future research.