The Children's Yale-Brown Obsessive Compulsive Scale-Symptom Checklist (CY-BOCS-SC; Scahill, L., Riddle, M. A., McSwiggin-Hardin, M., Ort, S. I., King, R. A., Goodman, W. K., et al. (1997). Children's Yale-Brown Obsessive Compulsive Scale: Reliability and validity. Journal of the American Academy of Child and Adolescent Psychiatry, 36, 844-852) is widely used to assess the presence of obsessions and compulsions in youth. Although factor analytic studies have established symptom dimensions of the CY-BOCS-SC, little is known of its psychometric properties. The present study sought to examine the convergent and discriminant validity of the CY-BOCS-SC. Eighty-six youth with obsessive compulsive disorder (OCD) and their parents were administered the CY-BOCS-SC, the CY-BOCS severity items, and the Anxiety Disorders Interview Schedule for DSM-IV: Parent Version (ADIS-IV-P). Children completed the Children's Depression Inventory and Multidimensional Anxiety Scale for Children. Internal consistency of CY-BOCS-SC symptom dimensions ranged from poor to good. The CY-BOCS-SC demonstrated good to excellent convergent validity, as demonstrated by large correlations with conceptually similar items on the ADIS-IV-P. The discriminant validity of the CY-BOCS-SC was also good, as evidenced by small, generally non-significant, correlations between the CY-BOCS-SC dimensions and depressive and anxiety symptoms, OCD symptom severity, and trichotillomania symptoms. These results provide initial psychometric support for the CY-BOCS-SC and support its use as a clinical and research instrument for assessing presence of a range of obsessive and compulsive symptoms in youth with OCD.