Background: Despite several studies on the concept of social capital in relation to health during the last two decades, the majority of these works have been conducted in developed countries. Purposes: This study examines the correlation between domains of social capital (reciprocity, trust, and social network) and physical activity level in an Iranian adult population. In addition, the study explores to find whether this relation is affected by socioeconomic status. Method: A total of 2000 questionnaires were distributed among adults living in 12 neighborhoods of Bandar Abbas city, Iran. Of this population, 1828 qualified questionnaires were utilized for further analysis. Results: High level of physical inactivity (62.3%) was reported by the participants. Discussion: Norms of reciprocity and neighborhood trust associated with the higher physical activity level among men and women. However, social network contributed to a higher level of physical activity among women group. The study indicated the correlation of socioeconomic variables with social capital indicators and physical activity level. Translation to Health Education Practice: Findings suggest that programming efforts and research should focus on increasing organized activities that support neighborhood participation and social activity to promote social interaction and trust among residents. A AJHE Self-Study quiz is online for this article via the SHAPE America Online Institute (SAOI) http://portal.shapeamerica.org/trn-Webinars