The purpose of this study is to provide an up-to-date estimate of the economic costs associated with autism spectrum disorders. There have been several comprehensive nation-specific cost estimates based on reviews of existing studies, sometimes combined with economic simulations. The current study builds on these studies in three ways. First, the investigators will include information from most recent studies of costs in different domains. Second, the investigators will provide estimates drawing on data from multiple countries, which may have more generalizability to all developed countries. Third and perhaps most importantly, the investigators will provide cost estimate trajectories specific to autism subtype, taking into account the potential effects of two types of interventions: intensive behavioral interventions delivered during the preschool period and vocational interventions designed to increase independence during the transition to adulthood. To develop this new estimate, studies of costs of autism will be reviewed from 1990 to the present day. Direct and indirect costs will be considered in the following categories: healthcare, education, caregiving, housing, and employment. To estimate the effects of interventions, the study team will conduct focus groups with international intervention experts to determine the range of potential outcomes for individuals across the autism spectrum. Decision analysis will then be used to determine how cost trajectories change as a function of effective intervention delivered at different points. Results will provide the most comprehensive estimate of the costs of autism to date, and provide specific information about the potential lifetime cost effectiveness of interventions delivered at different stages of life.