The purpose of the proposed study is to identify disparities in access to treatment for young children with autism spectrum disorders (ASD). In particular, this project will identify treatment that occurs both inside and outside the school system. This study will focus on disparities across multiple dimensions including race, region, socioeconomic status, and type of health insurance. While previous research has documented disparities in the age at diagnosis, an understanding of how this phenomenon translates to service use for children in early elementary school is lacking. The study design is observational and longitudinal relying on unique, nationally representative data generated from the Pre-Elementary Education Longitudinal Study (PEELS). The PEELS followed a nationally representative sample of over 3,000 preschool aged (age 3-5) children receiving special education services through 5 waves of data collection beginning in 2003-2004. The unweighted study sample includes approximately 450 children ever identified as having autism during the first 4 waves of data collection. Generalized estimating equations will be used to identify disparities in receipt of treatment services including speech, occupational, and physical therapies, behavior therapy or behavior management program, play therapy or group, and psychological or mental health services. The results of this analysis can be used to identify targets of intervention to reduce service disparities.