This document presents knowledge, skills, and attitudes that are needed for achieving and practicing the competencies listed in Addiction Counseling Competencies, as written by the National Curriculum Committee of the Addiction Technology Transfer Center Program. The document is intended to provide guidance for the professional treatment of substance use disorders, which has become recognized as a complex multidisciplinary practice supported by a large and rapidly expanding body of theoretical and scientific literature. The first section identifies the knowledge and attitudes that underlie competent practice not just for counselors but for addiction specialists in other disciplines as well. These foundations include: understanding addiction, treatment knowledge, application to practice, and professional readiness. The second section of the publication assesses the professional practice of addiction counseling. Using reviews of current research, input form key experts, and feedback from experienced trainers and practitioners, this section seeks to define the professional practice appropriate for the addiction counselor of the 21st century. Appendixes include the Addiction Counseling Competencies document and a glossary of terms. (Contains 84 references.) (GCP)