BackgroundFew studies have focused on the impact of neighborhood social environment on changes in smoking and alcohol use over time among African Americans. MethodJackson Heart Study participants were recruited from the Jackson, MS metropolitan area from 2000 to 2004. Neighborhood social environment was characterized using census-based neighborhood socio-economic status (NSES) and survey-derived perceptions of neighborhood social cohesion, disorder, and violence. Multinomial logistic regression was used to estimate the associations of neighborhood social environment with prevalence of smoking and alcohol use and with changes in these behaviors over time adjusted for individual sociodemographic characteristics. ResultsParticipants (N=3166) resided in 108 census tracts. All neighborhood social environment variables were consistently associated with prevalence of current smoking at baseline (11%) and with persistence of smoking over a median of 8-years follow-up (8%). The odds of being a consistent smoker relative to never smoking was about 30% higher per 1SD higher neighborhood violence (aOR: 1.30, 95% CI: 1.16–1.46) and disorder (aOR: 1.26, 95% CI: 1.08 – 1.47) and at least 16% lower per 1SD higher in neighborhood social cohesion (aOR: 0.84, 95% CI: 0.74–0.95) and NSES (aOR: 0.79, 95% CI: 0.67–0.95). Heavy alcohol use at baseline (17%) and consistent heavy use over the study period (8%) were negatively associated with higher NSES (aOR: 0.85, 95% CI: 0.73–0.99 per 1SD increase in NSES). ConclusionFavorable neighborhood social environments may reduce unhealthy behaviors among African Americans.