Objectives. To investigate the association between walkability and obesity, we studied adults residing in Baltimore City, Maryland, in neighborhoods of varying racial and socioeconomic composition. Methods. We conducted a cross-sectional study of 3493 participants from the study Healthy Aging in Neighborhoods of Diversity across the Life Span. We used the Pedestrian Environment Data Scan to measure neighborhood walkability in 34 neighborhoods of diverse racial and socioeconomic composition in which the study participants lived. Confirmatory factor analysis was used to determine walkability scores. Multilevel modeling was used to determine prevalence ratios for the association between walkability and obesity. Results. Among individuals living in predominately White and high-socioeconomic status (SES) neighborhoods, residing in highly walkable neighborhoods was associated with a lower prevalence of obesity when compared with individuals living in poorly walkable neighborhoods, after adjusting for individual-level demographic variables (prevalence ratio–[PR] = 0.58; P = <.001 vs PR = 0.80; P = .004). Prevalence ratios were similar after controlling for the perception of crime, physical activity, and main mode of transportation. The association between walkability and obesity for individuals living in low-SES neighborhoods was not significant after accounting for main mode of transportation (PR = 0.85; P = .060). Conclusions. Future research is needed to determine how differences in associations by neighborhood characteristics may contribute to racial disparities in obesity.