The influences of child participation in interest-based learning activities on the development of 17 preschoolers with autism was the focus of this brief report. The children's mothers identified their children's interests and the everyday family and community activities that provided opportunities for interest-based learning. Parents then implemented intervention procedures for 14 to 16 weeks to increase child participation in the selected activities. Based on an investigator-administered interestingness scale, the children were divided into high and low interest-based learning groups. The children's language, cognitive, social, and motor development quotients obtained at the beginning, the middle, and the end of the intervention were the dependent measures. Results showed that the high interest-based group made considerably more developmental progress compared to the low interest-based group. Implications for practice and future research are discussed.