Forty-six states and the District of Columbia have enacted insurance mandates that require commercial insurers to cover treatment for children with autism spectrum disorder (ASD). This study examined whether implementing autism mandates altered service use or spending among commercially insured children with ASD. We compared children age twenty-one or younger who were eligible for mandates to children not subject to mandates using 2008–12 claims data from three national insurers. Increases in service use and spending attributable to state mandates were detected for all outcomes. Mandates were associated with a 3.4-percentage-point increase in monthly use and a $77 increase in monthly spending on ASD-specific services. Effects were larger for younger children and increased with the number of years since mandate implementation. These increases suggest that state mandates are an effective tool for broadening access to autism treatment under commercial insurance.