Obsessive-Compulsive Disorder (OCD) is a disorder characterized by its clinical
heterogeneity, but also a commonality of symptom clusters that are known as “symptom
dimensions.” Previous research among clinical samples using factor analysis has shown that the symptom-structure of OCD falls into four or five of these dimensions. The symptom dimensions can be conceptualized as representing impairment in several discrete brain systems which may meet the criteria for evolved mental “modules.” The current study uses confirmatory factor analysis in a community sample to test several competing models of OCD-like symptoms. These symptoms are discussed from the perspective of adaptive mental modules, and normal functions of OCD-like thoughts and behaviors are discussed. The four-factor model of OCD symptoms proposed in previous research was supported relative to competing one and five-factor models, and a positive correlation between OCD-like symptoms and mating success is demonstrated. Implications are discussed for the understanding and treatment of OCD, as well as our understanding of the brain’s evolved cognitive structure and organization during normal functioning.