Background/Objective: Adult survivors of childhood cancer can have altered social functioning. We sought to identify factors that predict marriage and divorce outcomes in this growing population. Methods: This was a retrospective cohort study of 8,928 ≥5-year adult survivors of childhood malignancy and 2,879 random sibling controls participating in the Childhood Cancer Survivor Study. Marital status, current health, psychological status, and neurocognitive functioning were determined from surveys and validated instruments. Results: Survivors were more likely to be never-married than siblings [relative risk (RR), 1.21; 95% confidence interval (95% CI), 1.15-1.26] and the U.S. population (RR, 1.25; 95% CI, 1.21-1.29), after adjusting for age, gender, and race. Patients with central nervous system tumors were at greatest risk of not marrying (RR, 1.50; 95% CI, 1.41-1.59). Married survivors divorced at frequencies similar to controls. In multivariable regression analysis, nonmarriage was most associated with cranial radiation (RR, 1.15; 95% CI, 1.02-1.31 for >2,400 centigray). In analysis of neurobehavioral functioning, nonmarriage was associated with worse task efficiency (RR, 1.27; 95% CI, 1.20-1.35), but not with emotional distress, or problems with emotional regulation, memory, or organization. Physical conditions predictive of nonmarriage included short stature (RR, 1.27; 95% CI, 1.20-1.34) and poor physical function (RR, 1.08; 95% CI, 1.00-1.18). Structural equation modeling suggested that cranial radiation influenced marriage status through short stature, cognitive problems, and poor physical function. Conclusions: Childhood cancer survivors married at lower frequencies compared with peers. Patients with central nervous system tumors, cranial radiation, impaired processing efficiency, and short stature were more likely to never marry. Divorce patterns in survivors were similar to peers.