This study describes the relation between sleep problems and psychiatric symptoms in preschool-age children (3 to 5 years old) with pervasive developmental disorder and a community-based sample of children attending early childhood programs. Parents completed the Early Childhood Inventory-4, a Diagnostic and Statistical Manual of Mental Disorders (fourth edition)-referenced rating scale for 2 samples: children with pervasive developmental disorder (n = 112) and nondisabled youngsters (n = 497). Although children with pervasive developmental disorder had a significantly greater number and severity of sleep problems than the community preschoolers did, sleep-disturbed children in both samples exhibited more severe behavioral difficulties-primarily symptoms of attention-deficit hyperactivity disorder and oppositional defiant disorder-than did children without sleep problems. Sleep problems are an indicator of similar comorbid psychiatric symptoms in both children with and without pervasive developmental disorder, which suggests commonalities in their etiology.