Background & Objectives: Persistent Depressive Disorder (PDD) is defined as a depressive disorder with a minimum illness duration of two years, including 4 diagnostic subgroups (dysthymia, chronic major depression, recurrent major depression with incomplete remission between episodes, & double depression). A factor that persists in depression is rumination. Rumination is among the most problematic cognitive symptoms associated with depression. This study evaluated the effects of Emotional schema therapy (EST) that focuses on the individual's interpretations, strategies, and responses to emotions. Maladaptive schemas play an important role in the development or maintenance of depression. schema therapy (ST) is an integrative treatment approach to chronic lifelong problems. Treating depression–, induced rumination is essential in the treatment of psychological disorders. The current study aimed to compare the effects of EST and ST on rumination in patients with PDD (dysthymia). Methods: This was an expanded experimental project with pretest–, posttest–, follow–, up and a multi–, group design. Participating in the study was voluntary. The study sample consisted of 60 patients referring to Welfare Psychological Counseling Center in Shiraz Province, Iran, in 2017–,2018 who were selected and randomly assigned to the EST, groups, and control groups (n=20/group). The inclusion criteria were as follows: having at least a high–, school diploma degree, being aged from 20 to 50 years, providing a written consent form for cooperation in research, no substance use disorders, the absence of other psychological disorders, and no receipt of individual counseling or pharmacotherapy. The study groups completed the Ruminative Response Scale (RRS,Nolen–, Hoeksema & Morrow, 1991) at all measurement stages. The first experimental group participated in eight 90–, minute weekly sessions of EST based on Leahy et al. ’, s educational package (2011) for two months. The second experimental group participated in 10 one–, hour weekly sessions of ST based on the Young et al. ’, s package (2003) for 3 months. However, the control group received no treatment. Two months after the implementation of the posttest, the follow–, up phase was run. Descriptive statistics (mean & standard deviation) and inferential statistics, including one–, way Analysis of Variance (ANOVA), Chi–, squared test, repeated–, measures ANOVA, and Bonferroni post hoc test were applied in SPSS to analyze the obtained data. The significance level of the tests was considered 0. 05 Results: The current study results revealed that the effect of time (p<0. 001), group effect (p<0. 001), and the effect of time and group interaction on the mean scores of rumination were significant (p<0. 001). Furthermore, the mean scores of rumination in the EST group were significantly lower than those in the ST (p<0. 001) and control (p<0. 001) groups. Besides, the mean scores of rumination in the ST group were significantly lower than those in the control group (p<0. 001). There was a significant difference between the mean scores of rumination in the pretest and posttest stages (p<0. 001). There was also a significant difference between the mean scores of rumination in the pretest and follow–, up stages (p<0. 001),however, no significant difference was observed between the mean scores of rumination in posttest and follow–, up (p=0. 082). Conclusion: According to the research results, EST and ST can be used as effective methods to reduce rumination,however, EST was more effective than ST on rumination in patients with PDD (dysthymia).