Individuals (families, self-advocates, and practitioners) often advocate for autistic individuals to access services. Yet, there are few systems that accurately measure service access. To discern whether advocacy impacts service access, it is critical to have a measure of services. In this article, we share the development of the Service Inventory-a measure which includes operational definitions and probes of types of services relevant to autistic individuals across the lifespan. We share examples of the Service Inventory so it can be used by students, families, and behavior analysts as they advocate with autistic individuals to access services.