Autism spectrum disorders (ASDs) are among the most common of the severe developmental disabilities, yet little is known about older adults with ASDs—in particular, how the disabilities and dependencies that result from aging interact with those resulting from ASDs. The aging of the population in Western countries, the increasing rate of diagnosis of ASDs, and the burgeoning use of services for ASDs are converging to create a large, growing influx of older adults with ASDs that could impose tremendous humanistic and economic burdens on the healthcare system and society. An understanding of the epidemiological, biological, psychological, and social aspects of ASDs in older adults is essential for preparing to meet their needs, but studies on ASDs in these individuals are practically nonexistent. This article outlines observations and recommendations of a multidisciplinary expert group convened in March 2010 to characterize gaps in knowledge regarding ASDs in older adults and defines research directions to help individuals, the healthcare system, and society prepare for meeting the needs of this population. The proposed research agenda could help improve the lives of older adults with ASDs and inform research and clinical practice involving younger individuals with ASDs.