Families of children with autism spectrum disorder (ASD) play a central role in selecting interventions for their children. Despite the importance of understanding the factors that motivate early decisions about treatment, the literature has concentrated little attention on how and why parents of young children with ASD make decisions about services and supports. Using a collective case study design informed by a diverse sample, this study found a heavy reliance on formal and informal sources of support in guiding parents’ early treatment decisions for their young children with ASD. The Internet also served as a primary source of informational support to families. Findings highlight the importance of family support initiatives including peer-to-peer family mentoring and decision support aides to assist families in critically evaluating online and print information regarding ASD.