Aims: Commitment to marriage is of importance as a sustainable mechanism. It is one of the characteristics of successful and long-lasting marriages. Marital commitment is the strongest and most stable predictor of marital quality and stability. Therefore, this study aimed to examine the effects of self-differentiation treatment based on Bowen’s family system theory on couples’ marital commitment.

Materials and Methods: The research method was quasi-experimental with convenience sampling and one-month follow-up. The statistical population included clients who visited the counseling centers of Greater Tehran Police Command in the last quarter of 2018 and the first quarter of 2019. The sample included 30 couples, randomly assigned to the intervention and control groups (allocation ratio of 1:1). Marital commitment Questionnaire (Adams & jones, 1997) was utilized. The couples in the intervention group received ten 60-minute sessions of self-differentiation treatment by the researcher based on Bowen’s treatment system as group therapy over three months. The control group received no treatment. The follow-ups in both groups were performed after one month. The data analysis was done in the pre-test, post-test, and follow-up through repeated measures analysis of variance and mixed design.

Findings: The results indicated that the self-differentiation treatment was significantly effective in promoting marital commitment among couples of the intervention group compared to the controls (p=0.001). Furthermore, the results of the mixed design analysis indicated that the implementation of the independent variable was meaningful on all three components of Personal Commitment (p=0.001), structure Commitment (p=0.001) and Moral Commitment (p=0.004). This intervention’s results were also significant at the follow-up stage.

Conclusion: The self-differentiation treatment intervention based on Bowen’s family system theory effectively improved the couples’ marital commitment in the intervention group compared to the control group. The results of this research can be used in intervention planning with an emphasis on the role and importance of self-differentiation in the family to promote marital commitment and prevent couples from betraying each other, achieving timely prevention of divorce and emotional divorce picked up.