Aim: The goal of this study was to investigate the effect of Gottman's theory-based training on the reduction of couples' marital conflict and marital instability. Methods: The research method was quasi-experimental with the pretest-posttest control-group design, and the population of this study was comprised of all the married couples in Shiraz, Iran in 2015-16. They were selected by the convenience sampling method, and after the interview, and were randomly assigned into two (28) groups. To

more »

... llect the data, descriptive statistics such as mean, standard deviation, frequency and frequency percentage, as well as inferential statistics including analysis of covariance (MANCOVA) and (ANCOVA) were used to test the hypotheses. Subsequently, the experimental group was given the considered training during 7 sessions, and the questionnaires were, finally, completed again by both groups. Findings: Based on the findings of this study, Gottman's theory-based training has had a significant effect (α=0.05) on the reduction of marital conflict and marital instability of married couples. Conclusion: It was concluded that Gottman's theory-based intervention is able to reduce the level of marital conflict and its components and marital instability significantly in the experimental group.