The growth and advancement of community-based services for people with intellectual and developmental disabilities (IDD) have resulted in vast changes in the long-term services and support landscape as well as in expected outcomes of service systems for service recipients. Investments in IDD research have been made to provide a deeper understanding of these outcomes and to explain them. This article summarizes outcomes and their predictors through systems and individual lenses by examining the research and findings of the Administration on Intellectual and Developmental Disabilities' Data Projects of National Significance that address residential services, employment services, costs of services, and individual outcomes. The article also discusses challenges and debates associated with outcome-related research and poses future research questions.