The psychometric properties of a parent-completed developmental questionnaire for children at 6 years of age were investigated. Currently, few developmental screening instruments for 6-year-old children have been validated, and most available instruments are designed to be completed by teachers or professionals, who may not witness an optimal sample of child behavior. Thus a screening tool with robust psychometric properties is needed that can be completed by parents or caregivers who see the child across settings and time. A total of 169 children participated in this research. Data collection included online and paper completion during well child visits, in clinics, at preschool programs, and in parents' homes. A random subsample was asked to participate in reliability and convergent validity studies. Cronbach's alpha coefficient was used to measure internal consistency reliability. Results indicated a Cronbach alpha of agreement with the Child Development Inventory was used. A Confirmatory Factor Analysis with categorical data confirmed the 6-Year Ages and Stages Questionnaire domains, e.g., communication, personal social, fine motor, gross motor, and problem solving. Limitations of the current study and directions for future research are discussed.