--- - |2+ Abstract Objectives A shorter version of the Obsessive Beliefs Questionnaire (OBQ‐44) is needed to promote the use of this measure in research and increase our understanding of cognitive phenomena maintaining obsessive‐compulsive disorder (OCD). Additionally, an abbreviated version of the OBQ‐44 would encourage frequent monitoring of dysfunctional beliefs in intensive care settings. This study aimed to validate a nine‐item version of the questionnaire (OBQ‐9). Method Participants seeking intensive/residential treatment for OCD (N = 311) completed relevant measures on a weekly basis and at admission and discharge. Results A confirmatory factor analysis revealed that the OBQ‐9′s factor structure replicated the three‐factor solution of the OBQ‐44. The OBQ‐9 demonstrated good psychometric properties and convergent validity and was sensitive to treatment effects. Finally, the OBQ‐9 subscales predicted specific OCD dimensions over and above depressive symptoms. Conclusion The OBQ‐9 appears to be a psychometrically sound tool for routine outcome monitoring of dysfunctional beliefs in hospital‐based settings. - Journal of Clinical Psychology, EarlyView.