As part of the Harvard Cancer Prevention Program Project, we used a social contextual model of health behavior change to test an intervention targeting multiple risk-related behaviors in working-class, multiethnic populations. We examined the relationships between the social contextual factors in our conceptual model and changes in fruit and vegetable consumption from baseline to completion of intervention in health centers and small business studies. We analyzed change in fruit and vegetable consumption, measured at baseline and final assessments by self-report, in 2 randomized controlled prevention trials: 1 in small businesses (n = 974) and 1 in health centers (n = 1954). Stronger social networks, social norms that were more supportive, food sufficiency, and less household crowding were associated with greater change in fruit and vegetable intake. We also observed differences between our intervention sites. Social context can play an important role in promoting changes in fruit and vegetable consumption.