For young adults in the general population, maintaining close bonds to parental figures and being able to rely on them in times of need contributes to positive adjustment in the transition to adulthood, yet, the consequences of transitioning to adulthood without strong bonds to family has received remarkably limited attention. This systematic review synthesizes information about the relationships aging out foster youth have with their birth or stepparents after legally mandated separations in foster care. Utilizing PRISMA guidelines, published and unpublished information from studies recruiting US-based samples were reviewed, yielding 16 articles from 10 studies. Findings indicate (1) a majority of studies have reported information about foster youths’ self-reported contact with birth parents and post-foster care living arrangements, and (2) fewer studies have sought to identify the types of support provided by birth parents or explored the benefits and risks that come from different types of support. This review identifies the strengths and weaknesses of the existing evidence, highlights avenues for future research, and offers guidance for establishing practices around facilitating relationships.