At the present time, there is little consensus about how best to assess the quality of life (QoL) of adults with autism spectrum disorders (ASDs). Building on an existing longitudinal investigation of 406 individuals with ASD and their families, this research will use a multi-dimensional approach to explore QoL among individuals with ASD during early and middle adulthood. The study has three specific aims: (1) to reconceptualize QoL for adults with ASD and characterize the heterogeneity of QoL during early adulthood and midlife, (2) to identify factors that are associated with favorable QoL and adult outcomes during these life stages, and (3) to obtain self-reports and parent proxy-reports of QoL and a biomarker of aging (telomere length) from adults with ASD. Over the past 13 years, the investigators have interviewed families in their longitudinal study on 9 different occasions and have collected data on a variety of constructs including changes in autism symptoms, adaptive skills, behavior problems, health, employment, housing, social supports, and services of their son or daughter with ASD. Although there is increasing interest in the field regarding adult outcomes for individuals with ASD, the majority of past research has focused on the transition to adulthood. In contrast, little is known about the QoL of adults with ASD and how changes in autism symptoms, adaptive behaviors and other factors relate to QoL over their life course. This study focuses on two adult age groups drawn from the larger study: 48 adults in midlife (between the ages of 40 and 60) and a well-matched group of 48 adults in early adulthood (between ages of 25 and 39). The project team will use pre-existing data from a 13-year study as well as new data from a 10th interview with these families to collect information on how mothers evaluate QoL for their son or daughter with ASD. In addition, they will directly interview the adult with ASD to obtain his or her perspective on QoL. Also as part of this study, a biomarker of aging (telomere length) will be assessed to explore whether adults with ASD experience accelerated biological aging. By combining this new data collection with the researchers’ longitudinal data on trajectories of development, the study has the potential to yield unique knowledge about QoL for adults with ASD and the complex processes which may serve to improve or diminish QoL across the life course.