Abstarct: This research aims at assessing social capital of volunteers and non volunteers in universities’ sport associations through using exploratory factor analysis method. The methodology is a descxriptive –correlation research method. The statistical population of the research is made up of non volunteer and volunteer students who are members of Iranian universities’ sport associations among which 520 students(260 volunteer and 260 non volunteer) from 10 universities were selected, on the basis of random cluster sampling, as the research sample. A researcher- made questionnaire was administered to collect data and its content and face validity was already checked and confirmed by an expert university panel. Cronbach’s Alpha coefficient was used employed to test the reliability of the questionnaire (α=0.88). Then, the method of exploratory factor analysis with a varimax rotation was employed in order to recognize social capital factors and structural validity of the research factors and questionnaire. On this basis, twenty six social capital variables were classified into seven categories. The results show that the most important factor is “trust¬ (3.62±0.71)& (3.45±0.68)” and the least important factor is “partnership and team work (3.41±0.70)& (2.94±0.67)”.The research factors to be identified were determined by a combination of the following criteria: a) a pre-specification of the number of factors baxsed on the literature review; b) factors selection baxsed on eigenvalues greater than 1.0 (Kaiser criterion); c) visual inspection on the basis of the scree-plot; d) variance descxription criterion; and e) comprehensibility of the extracted factors. These seven scales accounted for 77.34%&80.31% of the variance in the item responses and were labeled as “partnership and team work, commitment, cooperation, trust, identification, information and awareness, empowerment and education”. The research suggests that sport organizations should, when using sport volunteers, pay a particular attention to social capital index and its related factors especially to the factor of trust that has a determining role.