Aim: The purpose of this study was to examine the effectiveness of Acceptance and Commitment Therapy (ACT) on reducing marital disaffection and increasing marital quality in women. Methods: This study was quasi -experimental with a pre-posttest, control and follow up design. Statistical population consisted of 2146 mothers of male students of three high schools in Central and Kelishad region of Felavarjan province in Iran during the 2015-16 academic year. 30 mothers were selected, and randomly assigned to an experimental and a control group (selection was based on participants’ availability and informed consent). Participants completed the Marital Disaffection Scale (Kaiser, 1993) and the Marital Quality Scale (Busby, Crane, Larsen & Christensen, 2008). The experimental group participated in 10 weekly, 90 minutes sessions of ACT (Hayes, 1986). Both groups completed the questionnaires at pre and post- test, and two months following the termination of therapy. Data was analyzed using multivariate analysis of covariance (MANCOVA). Result: Results showed that Acceptance and Commitment group therapy significantly decreased marital disaffection (F=15.881, P=0.001) and increased marital quality (F=8.594, P=0.001) of women in the experimental group comparing to the control group and these results were persistent at follow up. Conclusion: ACT can be considered as an effective intervention approach whereby applying metaphors, emotional regulation techniques and value-based commitment, can decrease marital frustration and increase marital quality in married women.