Studies of validity of a new caregiver report measure, the Children's Occupational Performance Questionnaire (COPQ) designed to address children's performance in the domains of personal and instrumental activities of daily living (IADLs), social participation, play/leisure, and education/work are presented. I examined criterion-related and discriminant validity of the COPQ. Criterion-related validity was addressed by correlating children's COPQ scores with those from the Vineland Adaptive Behavior Scale (VABS-II). Quasi-experimental methods were used to compare COPQ scores from a heterogeneous group of children with disabilities with those from neurotypical children matched by age. COPQ scores correlated highly with scores from the VABS-II including social interaction, communication, daily living skills, and motor skills. Capacity of the COPQ to discriminate between children with and without disabilities varied dependent on age, and the occupational domain being considered. Preliminary support for the validity of COPQ as a measure of occupational performance for children was provided. Further study of the tool's psychometrics and with larger samples is needed.