Autism spectrum disorder (ASD) is considered among the most heritable of all neurodevelopmental and psychiatric disorders, but identification of etiologically significant genetic markers and risk variants has been hampered by a lack of sufficiently large samples. Rapid phenotyping procedures, where self-report measures are used instead of extensive clinical assessment, have been proposed as methods for amassing large genetic databases due to their hypothesized time-efficiency and affordability. We assessed the diagnostic accuracy of potential rapid phenotyping procedures using the Social Communication Questionnaire and the Social Responsiveness Scale in a sample of 333 children who also received extensive phenotypic assessments. While the rapid phenotyping measures were able to accurately identify a large number of children with ASD, they also frequently failed to differentiate children with ASD from children with other complex neurobehavioral profiles. These data support the continued need of expert clinical validation in combination with rapid phenotyping procedures in order to accurately amass large-scale genetic collections of children with ASD. Autism Res2012,5:31–38. © 2011 International Society for Autism Research, Wiley Periodicals, Inc.