Autism research has grown rapidly over the past two decades, with about 350 peer-reviewed articles published in 1993 and more than 2,100 published last year. This major burgeoning in publication has been the result of many factors, including increased public (and funder) awareness, the activity of parents, parent support groups, and foundations, and the efforts of researchers, clinicians, and educators. Over the last several years, a number of major reference works have appeared, and Autism Spectrum Disorders joins the list as a distinguished entry.