An understanding of participation patterns in preschool-aged children with an autism spectrum disorder will allow the occupation therapy practitioner to focus on goals relevant to the child and family. This study compares participation patterns and barriers to participation in children with an autism spectrum disorder with those of children with no diagnosis. Using the Preschool Activity Card Sort, parent interviews revealed children with an autism diagnosis participate in fewer preschool activities of self-care, community mobility, vigorous leisure, sedentary leisure, social interaction, chores, and education than children with no diagnosis. Reasons for non-participation generally focused on child behaviors; parents gave opportunities to participate, but the child, for a variety of reasons, could not capitalize on the opportunity. Practitioners can assist the family in managing the child's responses and behavior in a wide range of preschool activities.