Relationships between the specific sleep problems and specific behavioral problems of children with autism were evaluated. Mothers' reports of sleep habits and autism symptoms were collected for 109 children with autism. Unlike previous research in this area, only children diagnosed with autism without any commonly comorbid diagnoses (e.g., intellectual disability, epilepsy) were included in the analysis. Consistent with prior work, a positive correlation between the severity of sleep problems and the severity of autism symptoms was obtained. Sleep onset delay and sleep duration were positively correlated with autism symptoms and autism severity. Sleep onset delay was the strongest predictor of communication deficit, stereotyped behavior, and autism severity. These results provide support for specific sleep problem and symptom relationships that are unique to autism and suggest the importance of including the treatment of sleep problems as part of a comprehensive behavioral intervention for children with autism. (Contains 2 tables.)