The aim of the current study was to examine cognitive and psychological factors hypothesized to affect responding to intrusions in obsessive-compulsive disorder (OCD). A group of individuals diagnosed with OCD was compared to a social phobia (SP) group and a nonclinical control group. Participants performed neuropsychological tasks, completed selfreport measures, and engaged in a self-relevant thought suppression task. The OCD group demonstrated worse working memory and response inhibition and had increased intrusions during the suppression task relative to comparison groups. They also reported more distress during the task relative to the nonclinical group, but not the SP group. Regression analyses revealed that beliefs about thought control failures, but not working memory or response inhibition, was associated with increased frequency of intrusions and greater distress during suppression. Findings support cognitive-behavioural models of OCD that emphasize the role of meta-beliefs in explaining the struggle with obsessional thoughts.