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AAIDD Announces the Publication of the 12th Edition of its Manual

January 15, 2021 [Silver Spring, MD]

The American Association on Intellectual and Developmental Disabilities (AAIDD) is proud to announce the publication of the 12th edition of Intellectual Disability: Definition, Diagnosis, Classification, and Systems of Supports.

Since its founding in 1876, the AAIDD has led the field in understanding, diagnosing, and classifying the construct of intellectual disability (ID). This important resource integrates the findings and developments of the last 10 years in a systematic approach to diagnosis, subgroup classification, and planning of systems of supports for people with ID. The 12th edition also presents an important change to the operational definition used in the of age of onset criterion for the diagnosis of ID.

This edition combines the conceptual thoroughness of past manuals with the practical aspects of a user’s guide, integrates knowledge that has emerged since the publication of the 11th edition of the AAIDD manual in 2010, and describes a systematic approach to the diagnosis, optional subgroup classification, and planning of supports for people with ID based on relevant models, purposes, and the evidence base.  Additionally, the 12th addition also contains Practice Guidelines that that frame best practices, enhance understanding, and facilitate precise, valid, and effective decision-making, recommendations, and actions.

The 12th edition authors, Robert L. Schalock, Ruth Luckasson, and Marc J. Tassé, with the assistance of an Advisory Committee of 32 international experts and the input of the Disability Experience Expert Panel of The Ohio State University Rehabilitation and Research Training Center on Health and Function for People With ID, present the field’s current understanding of ID and the best practice guidelines for defining, diagnosing, classifying, and providing supports to people with ID.

The members of the 12th edition Advisory Committee are: Giulia Balboni, Alexandra Bonardi, Serafino Buono, Wil H. E. Buntinx, Diego González Castañón, Atilla Cavkaytar, Luigi E. Croce, Deborah Fidler, Randy G. Floyd, Marty Ford, Sandra Friedman, Glenn T. Fujiura, Lisa Greenman, Susan M. Havercamp, Amy Hewitt, Yunji Jeong, Sheryl Larson, Kevin McGrew, Laura Lee McIntyre, Diane Morin, Elizabeth Perkins, Rick Rader, Anthony Rodriguez, Sofia Santos, Karrie A. Shogren, Peter J. Smith, Roger Stancliffe, James R.  Thompson, Miguel Ángel Verdugo, Mian Wang, Michael L. Wehmeyer, and Keith F. Widaman.

Click here to find Intellectual Disability: Definition, Diagnosis, Classification, and Systems of Supports in the AAIDD Bookstore.

For media questions and other requests, contact Dr. Margaret A. Nygren (


Founded in 1876, AAIDD is the oldest professional association concerned with intellectual and developmental disabilities. Learn more about the organization at

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