Growing interest in autism spectrum disorder (ASD) research requires increasingly large samples to uncover epidemiologic trends; such a large dataset is available in a national, web-based autism registry, the Interactive Autism Network (IAN). The objective of this study was to verify parent-report of professional ASD diagnosis to the registry's database via a medical record review on a sample of IAN Research participants. Sixty-one percent of families agreed to participate; 98% (n = 116) of whom provided documentation verifying a professionally diagnosed ASD. Results of this study suggest that information collected from parents participating in IAN Research is valid, participants can be authenticated, and that scientists can both confidently use IAN data and recruit participants for autism research.