The AAIDD definition manual leads the field in understanding, diagnosing, and classifying the construct of intellectual disability (ID). The 12th edition integrates the findings and developments of the last 10 years and presents the operational definition in a systematic approach to diagnosis, optional subgroup classification, and planning of systems of supports for people with ID. In addition, the 12th edition examines the construct of age of onset in light of the developments of the last 10 years and changes that criterion in a way that will be critically important for professionals in the field. The material in the 12th edition is presented in a user-friendly fashion and includes advance organizers for each chapter to facilitate easy access and understanding.
