AbstractBackgroundSocial isolation and connectedness are social determinants of health that have demonstrated effects on cancer‐related outcomes. These constructs have been systematically evaluated among pediatric and older adult cancer populations. In this review, the authors evaluated the prevalence, correlates, and psychosocial implications of social isolation and connectedness among young adult (YA) cancer survivors aged 18–39 years.MethodsPeer‐reviewed articles published in English before June 2021 were identified from database searches and included articles' reference lists according to PRISMA (Preferred Reporting Items for Systematic Reviews and Meta‐Analyses) guidelines. Included articles described studies that assessed social isolation and/or connectedness among YA cancer survivors.ResultsIn total, 5094 unique records were identified; 4143 were excluded after title/abstract screening, and 907 were excluded after full‐text review. Forty‐four articles were included. Few studies used validated measures or directly assessed social isolation or connectedness. Social isolation was similarly prevalent among YAs and older cancer survivors and noncancer populations. Demographic, clinical, and behavioral risk and protective factors for social isolation were identified. Social isolation was related to worse psychological well‐being, whereas social connectedness was often, but not always, related to better psychological well‐being.ConclusionsThis growing literature underscores the relevance of social isolation and connectedness as important health determinants among YA cancer survivors. The identified risk and protective factors can identify YAs who especially may benefit from screening for social isolation. Future studies are needed that directly, reliably, and validly evaluate social isolation and connectedness to inform the development of interventions to decrease isolation and increase connectedness.