This TIP on the best practice guidelines for the treatment of substance abuse is intended to enhance treatment providers' knowledge concerning people who have a physical or cognitive disability, in addition to their substance use disorder. The TIP is designed to educate clinicians, educators, and paraprofessionals about modifications needed in order to accommodate people in treatment for substance use disorders who have coexisting disabilities. It provides guidelines on methods of screening for disabilities and discusses treatment planning and counseling. Information on forming and maintaining linkages with other service providers is included. In making accommodations within a program for the disabled client, providers need to learn how to eliminate several groups of barriers to treatment: attitudinal barriers; discriminatory policies, practices, and procedures; and communication barriers. Appendixes include: "Bibliography,""Information Resources,""How to Refer to People with Disabilities,""Alcohol and Drug Programs and the Americans with Disabilities Act,""Resource Panel," and "Field Reviewers." (Contains approximately 150 references and 24 tables.) (JDM)