Although the occurrence of depression seems to be associated with many psychological variables, attachment, ruminative response styles and dysfunctional attitudes appear to be a significant feature in the emergence of depression. The current study included a total of 268 participants, 124 patients diagnosed with major depression and a healthy control group of 144 individuals. Accordingly, this study was aimed to compare the differences between individuals diagnosed with depression and control groups and different attachment styles groups (secure, preoccupied, fearful, and dismissive) in terms of the ruminative response styles (brooding and reflection) and dysfunctional attitudes (perfectionism/achievement and need for approval/dependency) in addition to depression and anxiety scores. The two-way ANOVA analysis determined that the main effect of group variables and attachment styles had a statistically significant effect on depression, anxiety, brooding, reflection, perfectionism/achievement and need for approval/dependency. People with a diagnosis of depression scored significantly higher than those in the control group from all dependent variables of the study. Moreover, in addition to ruminative response style and dysfunctional attitudes, depression and anxiety scores of individuals who have secure attachment style were lower compared to those with fearful and dismissive attachment styles. Post hoc comparisons of brooding and perfectionism/achievement variables performed based on attachment styles showed that individuals with secure attachment style differed from other groups in terms of each dependent variable. Post hoc comparisons for the variables of need for approval/dependency and reflection concluded that individuals who have secure attachment style differed from people with fearful and dismissive attachment style rather than those with preoccupied attachment style. Depression is one of the most common mental illnesses and the development of attachment-based psychotherapeutic interventions will contribute to better treatment.