Behaviour Research and Therapy 44 (2006) 137–146 The structure of childhood obsessions and compulsions: Dimensions in an outpatient sample $ Dean McKay a,Ã , John Piacentini b , Scott Greisberg a , Flemming Graae c , Margaret Jaffer c , Jillian Miller c a Department of Psychology, Fordham University, 441 East Fordham Road, Bronx, NY10458-5198, USA b University of California-Los Angeles, CA, USA c New York Presbyterian Hospital-Weill Cornell Medical Center, USA Received 22 July 2004; received in revised form 9 February 2005; accepted 14 February 2005 Abstract While obsessive-compulsive disorder (OCD) is defined as a unitary condition, prior research has identified meaningful and distinct symptom dimensions in adult samples. In contrast, there have been no investigations of symptom dimensions in samples of children diagnosed with OCD. The present study sought to address this gap. Children diagnosed with OCD (n ¼ 137) were administered the Children’s Yale- Brown Obsessive-Compulsive Scale symptom checklist and severity index. Symptoms were analyzed using principal components analysis. As with adult samples, four factors were identified from the checklist. However, these four factors (compulsions, sexual/aggressive obsessions, superstitions, and hoarding/ ordering/somatic concerns) were different in content from adult studies. Further, several symptoms significantly contributed to more than one dimension. Each dimension was significantly correlated with scores from the severity index, with the exception of the obsession score with the hoarding/ordering/somatic concerns factor. Results suggest that there are distinct dimensions of symptoms in childhood OCD, but that these dimensions do not correspond to those identified in adults. Instead, it appears that some factors share variance, and the dimensions themselves are separated based upon developmental trajectories. The ARTICLE IN PRESS www.elsevier.com/locate/brat 0005-7967/$ - see front matter r 2005 Elsevier Ltd. All rights reserved. doi:10.1016/j.brat.2005.02.001 $ Portions of these data were presented at the meeting of the World Congress of Behavioral and Cognitive Therapies, Vancouver, BC. We would like to thank Steven Taylor for very helpful comments on an earlier version of this manuscript. Ã Corresponding author. Tel.: +1 718 817 3775; fax: +1 718 817 3785. E-mail address: mckay@fordham.edu (D. McKay).