Civil society which is regarded as the highest form of society is a system in which citizens’ duties are well-defined and social participation is considered as a fundamental aspect of this kind of society. But for various reasons, citizens tendency to participate in public affairs is not equal. One of the reasons for this matter could be the presence or absence of trust at the micro- meso- and macro levels of the society. Trust and participation as key elements of social capital, which are directly related to social, economic, and political variables, have attracted the attention of many researchers. In this study, the relationship between thesetwo variables is being investigated. This is a survey research and the research population consisted of all the residents 18years and older of the city of Ham, of which 384 individuals were selected as the sample via a multi -stage cluster sampling technique. The data gathering tool was a research-made questionnaire that had face validity and the Cronbach’s coefficients for reliability for all the major variables were above 0.70. The results showed that the higher the levels of trust is among citizens, the greater is thier social participation (R=0.37). Also, generalized trust (0.58) and interpersonal trust (54.9) were relatively high among citizens, but trust in institutions (49.7) was relatively weak. Age and marital status were significantly related to social participation.