This study compared parent-reported sleep characteristics in 2- to 5-year-old children with autism spectrum disorders (ASD) to children with other developmental delays (DD) and typical development (TD). We included 529 children (303 ASD [167 males], 63 DD [46 males], and 163 TD [134 males]) enrolled in the CHARGE study, an ongoing population-based case-control study. The mean age of participants was 3.6 years (standard deviation, 0.8 years). ASD diagnosis was confirmed with Autism Diagnostic Interview-Revised (ADI-R) and Autism Diagnostic Observation Schedules (ADOS). Cognitive and adaptive functioning was assessed using Mullen Scales of Early Learning (MSEL) and Vineland Adaptive Behavior Scales (VABS), respectively. Demographic, medical and sleep history information were ascertained from California birth records, telephone interview, medical assessments at clinic visit, and parent-administered questionnaires. Fifty-three percent of children with ASD had at least one frequent sleep problem, followed by 46% of children with DD, and 32% of the TD group (P < 0.0001). Exploratory factor analyses of sleep history data yielded two factors: sleep onset problems and night waking. Children with ASD had marginally higher sleep onset factor scores and significantly higher night waking factor scores compared with the TD group. Factor scores for children with DD were intermediate between the ASD and TD groups. Cognitive or adaptive development did not predict severity of sleep problems in the ASD group.