Investigated examples of naturalistic humor in a group of 6 young children with autism and 6 age- and language-matched children with Down syndrome, who were videotaped while interacting with their mothers in bimonthly 1-hour sessions over the course of 1 year. Humor episodes were analyzed on three dimensions: cognitive developmental, social, and intentionality. The autistic children produced significantly less humor overall and less humor involving nonverbal incongruity. The only jokes in the study were told by 2 of the children with Down syndrome. Results indicate that while children with autism can produce and appreciate humor to a limited extent in a naturalistic setting, they do so at a significantly reduced level compared to matched controls. Findings are discussed in relation to the social-cognitive deficits in autistic children, which are among the primary characteristics of the syndrome.