The Simons Foundation has funded five university-based medical centers to identify and study a large number of individuals (~200 families within two years) with a recurrent genetic variation (deletion or duplication of segment 16p11.2) that increases their risk of developing autism spectrum and other neurodevelopmental disorders. The immediate goal is to identify medical, cognitive, neural and behavioral profiles shared by this genetically identified group. Families are recruited through web-based networks or referral by clinical genetic centers or testing laboratories. Extensive psychological and neurological testing and neuroimaging with a uniform protocol will take place at the collaborating medical centers. De-identified subject data and biospecimens will be available to qualified researchers worldwide. Careful analysis of genetically defined autism subtypes will allow detailed phenotypic comparisons within and between these groups to clarify genotype-phenotype correlations. Longer-term goals are to use these data to improve the quality of clinical care and to develop targeted interventions for individuals with autism.