There is growing evidence that efficacious interventions for autism are rarely adopted or successfully implemented in public mental health and education systems. We propose applying diffusion of innovation theory to further our understanding of why this is the case. We pose a practical set of questions that administrators face as they decide about the use of interventions. Using literature from autism intervention and dissemination science, we describe reasons why efficacious interventions for autism are rarely adopted, implemented, and maintained in community settings, all revolving around the perceived fit between the intervention and the needs and capacities of the setting. Finally, we suggest strategies for intervention development that may increase the probability that these interventions will be used in real-world settings.