This paper presents an empirical investigation to study the relationship between social capital and organizational commitment. The study considers the relationship between social capital with three components of organizational commitment; namely, affective commitment, continuous and normative commitment. The study has been applied among a sample of 292 regular employees who worked for an Iranian bank located in city of Tehran, Iran. The implementation of Pearson correlation has indicated that there were positive and meaningful relationships between social capital and affective commitment (r = 0.197, Sig. = 0.01), continuous (r = 0.308, Sig. = 0.01) and normative commitment (r = 0.423, Sig. = 0.01). In addition, the study has detected that women had more commitment on their organization than men did. The proposed study of this paper has also considered a regression model where organizational commitment is dependent variable and trust and communication are considered as independent variables. According to the results of regression analysis, an increase of one unit in trust and social capital communication will increase organizational commitment by 0.189 and 0.204, respectively.