International Review of Research in Mental Retardation is an ongoing scholarly look at research into the causes, effects, classification systems, syndromes, etc. of mental retardation. Contributors come from wide-ranging perspectives, including genetics, psychology, education, and other health and behavioral sciences. International Review of Research in Mental Retardation is now available online at ScienceDirect — full-text online of volumes 23 onwards. Elsevier book series on ScienceDirect gives multiple users throughout an institution simultaneous online access to an important compliment to primary research. Digital delivery ensures users reliable, 24-hour access to the latest peer-reviewed content. The Elsevier book series are compiled and written by the most highly regarded authors in their fields and are selected from across the globe using Elsevier’s extensive researcher network. For more information about the Elsevier Book Series on ScienceDirect Program, please visit: http://www.info.sciencedirect.com/bookseries/ Discusses the developmental epidemiology of mental retardation and developmental disabilities Explores the cutting edge methodological, statistical, and theoretical advances within the field Section I serves as an introduction, Section II reviews the various measurements, and Section III focuses on the epidemiological findings