en Epidemiology Epidemiology Original Research Original Research <p> <strong>Background:</strong> The aim of this study was to investigate the psychometric properties of Social Capital Questionnaire (SCQ) developed by Onyx and Bullen (2000) among a sample of medical science students in Tehran University of Medical Sciences, Iran and to compare the factor analysis with findings from two previous studies in Australia and the United States.</p><p> <strong>Methods:</strong> Multistage cluster sampling was employed to recruit 293 medical science students (Male: 95/Female: 198) from 7 faculties in Tehran University of Medical Sciences. After translating SCQ into Persian applying back-translation technique and three-stage consensus panel, the questionnaires administered to the respondents and they were asked to complete them. Statistical Analysis was performed using SPSS version 16.0 for Windows.</p><p> <strong>Results:</strong> Exploratory Factor Analysis (EFA) was conducted to evaluate factor structure of the Persian SCQ (PSCQ), which showed a moderate replicability, validity, and reliability (Cronbach alpha= .79) to those found in previous studies. Twelve factors extracted with eight values greater than 1 which altogether accounted for 76.23% of the total variance. Applying Cattell's scree test, it was indicated that between seven and eight factors extracted. The correlations between factors were detected in the low (at the lowest 0.002) to modest (at the highest 0.614) range.</p><p> <strong>Conclusion:</strong> The differences found in the factor analysis between the studies may be ascribed to the various types of populations studied. Despite the difference in populations studied, our findings support the meaningfulness of P-SCQ as an instrument that is worthy of further attention for use in social health researches, although more studies are recommended to help researchers in comparing its variety in dimensions of different communities.</p> Social Capital, Factor Analysis, Construct Validity, Iran. 107 118 http://mjiri.iums.ac.ir/browse.php?a_code=A-10-1-645&slc_lang=en&sid=1 Arezoo Yari yariarezoorose@gmail.com 200319475328460012971 200319475328460012971 No Kurdistan Research Center for Social Determinants of Health (KRSDH),Kurdistan University of Medical Sciences, Sanandaj, Iran. Haidar Nadrian nadrian@razi.tums.ac.ir 200319475328460012972 200319475328460012972 Yes Department of Health Education and Promotion, School of Health and Health Research Institute, Tehran University of Medical Sciences, Iran. Hamideh Rashidian hmdhrashidian@yahoo.com 200319475328460012973 200319475328460012973 No School of Health, Kerman University of Medical Sciences, Kerman, Iran. Saharnaz Nedjat nejatsan@tums.ac.ir 200319475328460012974 200319475328460012974 No Department of Epidemiology and Biostatistics, School of Health, Knowledge Utilization ResearchCenter, Tehran University of Medical Sciences, Tehran, Iran. Nader Esmaeilnasab esmailnasab@yahoo.com 200319475328460012975 200319475328460012975 No School of Medicine, Kurdistan University of Medical Sciences, Kurdistan, Iran. Rajabali Doroudi daroudir@gmail.com 200319475328460012976 200319475328460012976 No School of Health and Health Research Institute, Tehran University of Medical Sciences, Tehran, Iran. Haydeh Hoursan h_hoorsan@yahoo.com 200319475328460012977 200319475328460012977 No Department of Nursing & Midwifery, Sanandaj Branch, Islamic Azad University, Sanandaj, Iran.