One of the factors that play a role in the emergence and persistence of obsessive-compulsive symptoms might be childhood neglect and abuse. The main aim of this study was to examine the mediating role of worldview assumptions and the severity of obsessive beliefs in the relationship between childhood traumas and the severity of obsessive-compulsive symptoms. Furthermore, gender differences in childhood traumas, worldview assumptions, obsessive beliefs, and obsessive-compulsive symptoms were investigated. Five hundred sixty-two college students (M-age = 21.54, SD = 3.60; 113 male, 449 female) completed Childhood Traumas Scale, Worldview Assumptions Scale, Obsessive Beliefs Questionnaire, and Vancouver Obsessive-Compulsive Inventory via electronic mail. It was found that both worldview assumptions and severity of obsessive beliefs have mediating roles in the relationship between the frequency of childhood traumas and the obsessive-compulsive symptom severity. More specifically, the relationship between the frequency of childhood traumas and severity of obsessive-compulsive symptoms was mediated by negative worldview assumptions through the severity of obsessive beliefs. In addition, none of the variables revealed gender difference. The results of the study shed light on the complex mechanism in the relations between childhood traumas and obsessive-compulsive symptoms. Results also imply that inquiry of childhood neglect and abuse, negative worldview assumptions, and obsessive beliefs may contribute to the treatment of obsessive-compulsive symptoms.