The Simons Simplex Collection (SSC) is a core project and resource of the Simons Foundation Autism Research Initiative. The SSC achieved its primary goal to establish a permanent repository of genetic samples from 2,700 families, each of which has one child affected with an autism spectrum disorder, and unaffected parents and siblings. Each genetic sample has an associated collection of data that provides a precise characterization of the individual (phenotype). Rigorous phenotyping maximizes the value of the resource for a wide variety of future research projects on the causes and mechanisms of autism. The SSC is operated by SFARI in collaboration with 12 university-affiliated research clinics.