Background: Survivors of childhood cancer are at risk for obesity and associated chronic health conditions - risks that are potentially modifiable if survivors adopt a lifestyle with adequate physical activity and a healthy diet. Neighborhoods where survivors reside may influence uptake of health behaviors. We examined associations between neighborhood factors and obesity in survivors. Methods: Adult survivors participating in the St. Jude Lifetime cohort with addresses available for geocoding were eligible for analysis [N = 2265, mean assessment age 32.5 (SD 9.1) years, 46% female, and 85% white]. Survivors completed questionnaires regarding individual behaviors; percent body fat was assessed via dual x-ray absorptiometry (obesity: ≥25% males; ≥35% females); and neighborhood effects were characterized using census tract of residence (e.g. neighborhood socioeconomic status (SES), rurality). Structural equation modeling (SEM) was used to determine associations between neighborhood effects, physical activity, diet, smoking, treatment exposures, and obesity. Results: Obese survivors (n = 1420, 62.7%) lived in neighborhoods with less access to exercise opportunities (63% vs 66%, p = 0.01) and lower SES (22% vs 18%, p < 0.001); and were more likely to live in small town/rural areas (14% vs 10%, p = 0.04) compared to non-obese survivors. Obese survivors who lived in the lowest SES neighborhoods were more likely to be CNS tumor survivors (17% vs 12%, p = 0.02) and received higher mean doses of cranial radiation (CRT) (15Gy vs 11Gy, p = 0.02) than obese survivors living in higher SES neighborhoods. Resource poor neighborhoods (standardized effect: 0.09, p < 0.001) and CRT (0.14, p < 0.001) had direct effects on percent body fat. Associations between neighborhood of residence and percent body fat were attenuated (-0.02, p < 0.001) among individuals with a better diet. Conclusions: The neighborhood in which a childhood cancer survivor resides as an adult is associated with obesity, and obese survivors treated with CRT are more likely to live in neighborhoods with lower SES. Interventions targeting survivors should incorporate strategies that address environmental influences on obesity.