Cognitive models of obsessive-compulsive disorder (OCD) posit that specific kinds of dysfunctional beliefs (e.g., pertaining to responsibility and the significance of intrusive thoughts) underlie the development of this disorder. The present study was designed to prospectively evaluate whether dysfunctional beliefs thought to underlie OCD act as a specific vulnerability factor in the pathogenesis of obsessive-compulsive symptomatology. Eighty-five individuals were prospectively followed over a period of time thought to be associated with an increased onset of OCD symptoms -- childbirth and the postpartum. The majority of these new mothers and fathers experienced intrusive infant-related thoughts and performed neutralizing behaviors similar to, but less severe than, those observed in OCD. Scores on a measure of dysfunctional beliefs thought to underlie OCD predicted the development of obsessive-compulsive symptoms after controlling for pre-existing OCD symptoms, anxiety, and depression. Dysfunctional beliefs also predicted the severity of checking, washing, and obsessional OCD symptom dimensions, but not neutralizing, ordering, or hoarding symptom dimensions. These data provide evidence for specific dysfunctional beliefs as risk factors in the development of some types of OCD symptoms.