BackgroundMarital conflicts and divorce are among the most crucial problems of society. Therefore, it is important to maintain family stability at the optimal level in order to prevent divorce and its consequences in the family and community.ObjectiveThis study was conducted to design and validate the Family Stability Questionnaire (FSQ) in married couples.MethodsThis study was the second stage of a large study. The FSQ was constructed based on a qualitative research in our previous study in 2016. It was developed through interviews by family therapists, psychiatrists, and couples on 10 dimensions (areas) and was based on McMaster’s Family Assessment Device (FAD). Then, in the present study, a confirmatory factor analysis was conducted on 270 males and females (135 couples) of Yazd City (Iran) from January to May 2017. The construct validity and reliability of the scales were examined using exploratory and confirmatory factor analyses (EFA and CFA) and Cronbach’s alpha coefficient, respectively. Test-retest reliability was assessed with intra-class correlation coefficients (ICC) for the agreement between the individual items and domains. SPSS 21 and AMOS 21 were used for statistical analyses (p≤0.05).ResultsAt first, the results of the CFA on 70 items of FSQ could not confirm (RMSEA=0.06, CFI=0.91, GFI=0.72), but FSQ with 56 questions indicated that it had sufficiently high validity and reliability to measure family stability (RMSEA=0.04, CFI=0.95, GFI=0.96) with an acceptable fit index. A positive significant correlation was observed between the FSQ and FAD (r=0.45, p<0.001) indicating that FSQ has convergent validity. The Cronbach’s alpha and ICC of more than 0.7 in 10 domains of this tool indicated a good internal consistency among the items and their high relevance (0.90 and 0.84, respectively).ConclusionFSQ, as a multi-dimensional questionnaire, is a useful and reliable instrument to assess family stability. It consists of ten factors, which were constructed for the first time in Iran. Given the proper features, this instrument can be utilized to carry out more research regarding family stability in Iranian populations.