The aim of this study was to identify child characteristics, family demographics, and parent cognitions that may affect access to early intervention, special education, and related services. The sample included 70 families of young children with autism spectrum disorders. All parents were enrolled in a short education program, providing them with basic information and resources on advocating for a young child with autism spectrum disorders (Parent Advocacy Coaching). Longitudinal change in children's intervention program in the community was evaluated over a period of about 27 months, starting 12 months prior to enrollment in Parent Advocacy Coaching. Results revealed large individual differences in the intensity of children's individual and school-based services. Despite this variability, only two child characteristics (age, gender) emerged as independent predictors. In contrast, the intensity of children's intervention programs was independently predicted by a broad range of demographic characteristics, including parental education, child ethnicity and race, and family composition. Finally, even after child characteristics and family demographics were statistically controlled, results revealed associations between specific parental cognitions (parenting efficacy, understanding of child development) and the subsequent rate of change in the intensity of children's intervention programs. Implications for improving educational programs that aim to enhance parent advocacy are discussed.