Background:Relative to their counterparts in the general population, young people who leave, or transition out of, out-of-home (OOHC) arrangements, commonly experience poorer outcomes across a range of indicators, including: higher rates of homelessness, unemployment, reliance on public assistance, physical and mental health problems, and contact with the criminal justice system. The age at which young people transition from OOHC varies between and within some countries, but for most, formal support ceases between the ages of 18 and 21.Programs designed to support transitions are generally available to young people toward the end of their OOHC placement, although some can extend beyond. They often encourage the development of skills required for continued engagement in education, obtaining employment, maintaining housing and general life skills. Little is known about the effectiveness of these programs, or of extended care policies that raise the age at which support remains available to young people after leaving OOHC. This systematic review will seek to identify programs and/or interventions that improve outcomes for youth transitioning from the OOHC system into adult living arrangements.Methods:Using the Preferred Reporting Items for Systematic Review and Meta-analysis Protocols (PRISMA-P) guidelines, this review will identify programs, interventions and policies that seek to improve health and psychosocial outcomes amongst this population that have been tested using robust controlled methods. Primary outcomes of interest are homelessness, health, education, employment, exposure to violence and risky behaviour. Secondary outcomes are relationships and life skills. A search strategy has been developed that covers eleven databases of published literature in multiple languages. Unpublished literature will also be searched. A meta-analysis will be undertaken if identified studies are suitably heterogenous. Risk of bias will be assessed using tools appropriate to the study methodology. Outcomes across studies will be assessed using the Grading of Recommendations, Assessment, Development and Evaluation (GRADE) methodology.Discussion:Previous reviews were unable to identify any programs or interventions, backed by methodologically rigorous research, that improve outcomes for this population. This review seeks to update this previous work, taking into account changes in the provision of extended care, which is now available in some jurisdictions. Trial Registration:PROSPERO: CRD42020146999