Research has shown that although intrusive thoughts occur universally, the majority of individuals do not view intrusive thoughts as being problematic (Freeston, Ladouceur, Thibodeau, Gagnon, 1991; Rachman de Silva, 1978; Salkovskis Harrison, 1984). Thus, it is not the presence of intrusive thoughts that leads to obsessional problems but rather some other factor that plays a role in the development of abnormal obsessions. According to the cognitive model of obsessive- compulsive disorder (OCD) put forth by Salkovskis (1985), the crucial factor that differentiates between individuals with OCD and those without is the individual s appraisal of the naturally occurring intrusive thoughts. This study aimed to test Salkovskis s model by examining the role of cognitive biases (responsibility, thought-action fusion, and thought control) as well as distress in the relationship between intrusive thoughts and obsessive-compulsive symptoms in an undergraduate sample of 326 students. An existing measure of intrusive thoughts (the Revised Obsessional Intrusions Inventory) was modified for this study to include a scale of distress associated with each intrusive thought in addition to the current frequency scale. When the Yale-Brown Obsessive- Compulsive Scale was used as the measure of OCD symptoms, a significant interaction effect of frequency and distress of intrusive thoughts resulted. Additionally, a significant three-way interaction of Frequency ? Distress ? Responsibility was found when the Obsessive Compulsive Inventory-Revised was used as the measure of OCD symptoms. These results indicate that the appraisal of intrusive thoughts is important in predicting OCD symptoms, thus providing support for Salkovskis s model of OCD.