Participation in activities provides the means for young children to learn, play, develop skills, and develop a sense of personal identity. The Assessment of Preschool Children's Participation (APCP) is a newly developed measure to capture the participation of children aged 2 to 5 years and 11 months in the areas of play, skill development, active physical recreation, and social activities. Data from a clinical trial involving 120 children with cerebral palsy indicated that the APCP has moderate to very good internal consistency. The measure distinguishes between children below or above 4 years of age across levels of the Gross Motor Classification System, and between income levels below or above the median regional income range. The APCP, with a focus on preschool children, has potential use for assessment and identification of activity areas in which the child is participating and areas in which participation may be restricted. (Contains 5 tables and 1 footnote.)