This Treatment Improvement Protocol (TIP) provides guidelines for counselors and others working in the field of co-occurring substance use and mental disorders. TIPs are best-practice guidelines for the treatment of substance use disorders that make the latest research in substance abuse treatment available to counselors and educators. The content was generated by a panel of experts in the fields of substance abuse treatment and mental health, and reviewed by independent experts. The nine chapters include selected literature reviews, synopses of many treatment approaches for co-occurring disorders, and empirical information. Terminology, assessment, treatment strategies and models, and an overview of specific mental disorders and cross-cutting issues, such as suicidality and nicotine dependency, are explored in detail. Appended are: (1) Bibliography; (2) Acronyms; (3) Glossary of Terms; (4) Specific Mental Disorders: Additional Guidance for the Counselor; (5) Emerging Models; (6) Common Medications for Disorders; (7) Screening and Assessment Instruments; (8) Sample Screening Instruments; (9) Selected Sources of Training; (10) Dual Recovery Mutual Self-Help Programs and Other Resources for Consumers and Providers; (11) Confidentiality; (12) Resource Panel; (13) Cultural Competency and Diversity Network Participants; and (14) Field Reviewers.