This review critically summarizes the literature on neighborhood determinants of obesity and proposes a conceptual framework to guide future inquiry. Thirty-seven studies met all inclusion criteria and revealed that the influence of neighborhood-level factors appears mixed. Neighborhood-level measures of economic resources were associated with obesity in 15 studies, while the associations between neighborhood income inequality and racial composition with obesity were mixed. Availability of healthy versus unhealthy food was inconsistently related to obesity, while neighborhood features that discourage physical activity were consistently associated with increased body mass index. Theoretical explanations for neighborhood-obesity effects and recommendations for strengthening the literature are presented.