Co-occurring Mental Illness and Substance Use Disorders: A Guide to Diagnosis and Treatment presents an evidence-based approach to patients with at least two psychiatric disorders, one of which relates to substance use. Because co-occurring disorders are more the rule than the exception in psychiatry, the editors emphasize that patients should be carefully evaluated for a broad range of disorders, which should then be addressed clinically. The range of psychiatric disorders and the number of substances of abuse create complexity that can feel overwhelming to clinicians, and the book addresses this challenge by providing straightforward strategies for diagnosing and treating people with complicated presentations. The chapters are case-based and written in an accessible style that highlights commonalities, thus making it easy to understand and apply. Co-occurring Mental Illness and Substance Use Disorders: A Guide to Diagnosis and Treatment tackles a complicated subject area with rigor and real-world expertise, improving the standard of care delivered by clinicians who work with this population as well as the lives of the many people who suffer with these co-occurring disorders.