Nowadays, social capital plays a more important role in human societies than physical and human capitals and the networks of collective relations functions as a cohesive force between people and organizations. Social development, cultural progress and economic growth become almost impossible without the existence of social capital. It appears that understanding the various dimensions of organizational performance of the municipality can enhance the promotion of social capital. In this regards, the present study aims to explain the effects of organizational performance of the municipality on residents’ levels of social capital in Tehran’s 15th district. Therefore, the research population consists of all the residents of that district, of which 447 individuals were chosen as the sample. A questionnaire was used to collect the necessary data. Correlation coefficients and structural equation modeling were used to analyze the data. The results showed that, in line with the main hypothesis of the paper, the organizational performance of the municipality does in fact have positive effects on residents’ levels of social capital. The results of structural equation modeling indicated that “socio-cultural performance”, “transportation and traffic performance”, “urban services performance”, and “technical-construction performance” had, respectively, the most impact on social capital. In the area of social capital, “internal trust”, “generalized trust”, “participation in voluntary activities”, “mutual social participation”, and “the feeling of identity” were of the most significance.