Background: The family, as the smallest and the most infl uential unit of society, plays a pivotal role in the development of personal, social, and human values. Objectives: The current study aimed at developing and psychometrically evaluating the SUCCESSFUL MARRIAGE factors questionnaire in youth. Methods: The current methodological study was designed in two stages. In stage one, a qualitative conventional content analysis was conducted SUCCESSFUL couples and experts in MARRIAGE-related fi elds. By using the obtained results, a 129-item instrument was designed. In stage two, the qualitative and quantitative face and content validity, as well as the convergent and construct validity, were measured, and the reliability of the instrument was assessed. Cronbach’ s alpha and test-retest reliability were employed to determine internal consistency and estimate the stability, respectively. Results: After assessing face and content validity, 129 items were reduced to 80; then the construct validity was performed using the exploratory factor analysis (EFA), and then a 62-item SUCCESSFUL MARRIAGE factors questionnaire (SMFQ) was formed. The convergent validity of the tool was measured by the 47-item ENRICH marital satisfaction scale (EMS), and a signifi cant correlation was found between the total score of the 47-item EMS and its dimensions and those of constructs and entire SMFQ. In the third stage, the internal consistency reliability (Cronbach’ s alpha) and stability of the instrument were estimated, which were 0. 969 and 0. 962, respectively. The total minimum and maximum scores of the questionnaire are 62 and 310, respectively. Conclusions: A 62-item SMFQ was developed and psychometrically evaluated in the present cultural context of Iran, and it was a valid and reliable scale for the evaluation of factors aff ecting the SUCCESSFUL MARRIAGE.