The social environment is important to body mass index and obesity. However, it is unknown if perceptions of the social environment are associated with obesity-related behaviors in populations at greatest risk for being overweight or obese. We evaluated the relationship between collective efficacy and diet and physical activity in a community-based sample of African American adults who were residents in an urban area. Data were collected as part of an academic-community partnership from November 2009–2011. We evaluated whether participants met the recommended guidelines for diet and physical activity based on collective efficacy and their sociodemographic background, health care variables, and self-efficacy in a community-based sample of African American adults (n=338) who were residents in the Philadelphia, PA metropolitan area. Overall, many participants did not meet the recommended guidelines for fruit and vegetable intake or physical activity. The likelihood of meeting the recommended guidelines for fruit intake increased with greater levels of collective efficacy (OR=1.57, 95% CI=1.18, 2.07, p=0.002) and self-efficacy for diet (OR=1.56, 95% CI=1.19, 2.04, p=0.001). Collective efficacy was not associated with physical activity and the positive association between collective efficacy and vegetable intake was not statistically significant (OR=1.25, 95% CI=0.94, 1.65, p=0.12). It is important to determine the most effective methods and settings for improving diet and physical activity behaviors in urban African Americans. Enhancing collective efficacy may be important to improving adherence to recommended guidelines for obesity-related health behaviors.