The objectives of this systematic review were to synthesize available information on social support and social networks among individuals experiencing chronic homelessness, examine the measurement of social support, the impact of social support on outcomes, and the impact of interventions on social support. The authors searched Academic Search Complete, PsycArticles, Pubmed, PsycINFO, ScienceDirect, Cinahl, and ProQuest for English-language empirical articles published between 1998 and 2019. Studies were included if they sampled single and unaccompanied adults experiencing chronic homelessness and examined the impact of social support and/or social networks. The search yielded 29 studies. Results were synthesized according to research questions and patterns of findings that emerged from included studies. Wide variability in the measurement of social support was found across studies. Nearly all studies found changes in social support associated with housing interventions. A substantial evidence base indicated intervention effects on social support are largely positive. Review findings suggest individuals with substance use disorders may require additional social functioning support once housed. Indigenous people may require tailored interventions to center their cultural values and facilitate existing community strengths. Overall, the results from this review suggest social support plays a key role in the housing experiences and outcomes of individuals experiencing chronic homelessness. Future studies should include qualitative and mixed methods work as these methods revealed important insights about social support. More evidence is needed to inform the development of specific interventions targeting social support to facilitate community integration of formerly homeless individuals. (PsycInfo Database Record (c) 2022 APA, all rights reserved).