While there has been great progress in understanding the risks contributing to autism spectrum disorders (ASD), there are still unanswered questions about the nature of the genetic and non-genetic risks for autism. Many of these questions can be best addressed with a population-based epidemiological sample with detailed demographic and environmental information. Epidemiologically based samples provide a unique resource to identify genetic and non-genetic causes of autism, while allowing for a precise estimate of risk in the population. Sweden benefits from a centralized medical system that has been the foundation of large-scale epidemiological studies in psychiatric disorders, particularly schizophrenia and bipolar disorder. This study presents a unique, population-based epidemiological sample in Sweden that will be evaluated for estimations of heritability and identification of rare, genetic variation conferring risk to autism, while providing an integrated model for genetics and environment in autism. This project aims to provide the groundwork for understanding shared risk across autism and schizophrenia, making use of a specific human population that permits identification of shared risk. This approach addresses many of the open questions in autism research and provides a path towards a better understanding of the risk factors for autism and ultimately to better interventions in autism.