This document, the result of the collaborative efforts of the members of the Prime Study Group of the Institute on Rehabilitation Issues, provides information concerning techniques, strategies, models, and resources for rehabilitation professionals who are working with persons with coexisting abuse problems and disabling conditions. Chapter I, an introduction, defines "coexisting disability," outlines prevalence and incidence, examines multicultural issues, and explores personal and social attitudes about substance abuse. Chapter II addresses the medical aspects of substance abuse, covering the classification of substances; effects on the central nervous system; pharmacology; and interaction of substances with physical, cognitive, mental, and emotional disabilities. Chapter III considers assessment of substance abuse as a coexisting disability, with special attention given to the diagnostic interview. It describes signs and symptoms of substance abuse, criteria for psychoactive substance dependency, and methods of detecting substance abuse. Chapter IV covers the definition of treatment, intervention strategies, the need for family involvement, and interagency cooperation. Chapter V begins with the vocational rehabilitation counselor's responses to substance abusing clients and then addresses resources and networking, confidentiality, and appropriate methods for sharing information. Chapter VI discusses how traditional substance abuse treatment programs fail to meet the needs of many persons with disabilities and discusses ways to develop more accessible treatment programs. Chapter VII addresses job development and placement in cases of substance abuse as a coexisting disability. Appendices contain the 12-step model for addiction recovery, a glossary of drug street language, and an annotated list of 19 suggested readings. (Each chapter contains references.) (JDD)