"This book is designed as a tool for graduate students studying to become professional counselors who will work in a variety of settings, including healthcare agencies and treatment facilities. It is highly likely that all counselors, regardless of their specialty or work environment, will encounter clients struggling with a co-occurring mental and substance use disorder (COD). National statistics highlight this sentiment: In 2020 there were 52.9 million U.S. adults with a past-year mental illness (MI), 14.2 million with a serious mental illness (SMI), 20.9 million with a past-year substance use disorder (SUD), and an additional 17.0 million with both MI/SMI and SUD- also known as a COD (Substance Abuse and Mental Health Services Administration [SAMHSA], 2021). While these numbers represent adults over the age of 18, adolescents also experience CODs with elements of either disorder emerging throughout adolescence and into adulthood. Professional counselors who work with clients need to be aware of the overlap between substance use disorders and mental disorders in order to identify, intervene, and provide ethical and competent treatment. This book is also a resource for established counselors who did not receive comprehensive education while in their training program yet find themselves working with clients who have CODs. Unique to this book is the focus on the profession of counseling. Both editors and the majority of contributing authors are all professional counselors-many of whom are counselor educators and clinical supervisors-with direct care experience working with individuals diagnosed with CODs. Being grounded in the counseling profession offers a holistic, wellness perspective that is often missing from books on co-occurring disorders primarly written by professionals with medical degrees or other behavioral health backgrounds. CONTENT This book is designed to be a straightforward, yet comprehensive text that provides counselors-in-training and counselors in clinical practice a thorough review of co-occurring mental and substance use disorders (CODs). The text is divided into four main sections: SECTION I: CONSIDERATIONS FOR TREATING CO-OCCURRING DISORDERS Using a step-wise fashion, the text begins by creating the groundwork by introducing the concept of CODs in Chapters 1, 2, and 3. Chapter 1 offers a general overview (including the prevalence) of CODs, describes etiological paradigms and risk factors for developing CODs, and outlines the guiding principles for working with individuals who have CODs as recommended by the Substance Abuse and Mental Health Services Administration (SAMHSA). Chapter 2 provides a brief overview of addictive disorders, both substance-related and behavioral addictions. Information includes commonly abused substance of abuse, distinct models of addiction etiology, and the DSM classification system. Chapter 3 provides a comprehensive introduction to the neuroscience of CODs. SECTION II: TREATMENT APPROACHES Section 2 transitions the reader to their work with future clients, including specific treatment procedures common to all counselors. This consists of chapters exploring the screening, assessment, and evaluation processes; the various levels of care in which clients may receive treatment; and useful information that clients may encounter once they enter into treatment. Chapter 4 provides an overview of screening, assessment, and evaluation of CODs. Readers will gain a general overview of treatment and recovery plan development to guide their future work with clients in the initial encounter. Chapter 5 provides details regarding the levels of care options for clients. This includes managed care admission guidelines based upon medical necessity and a discussion of the American Society of Addiction Medicine's (ASAM) six dimensions of multidimensional assessment and Patient Placement Criteria-2. In addition, this chapter explores community supports for clients with CODs. Chapter 6 introduces readers to the Transtheoretical Model of Change and explores motivational interviewing/motivational enhancement therapy. In addition, person-centered/humanistic and cognitive-behavioral theories for treating CODs are discussed. Relapse mechanisms, relapse prevention, and longer-term recovery maintenance are described. Chapter 7 provides a general overview of psychopharmacology/pharmacotherapy as it relates to working with people who have CODs. This attends to both behavioral health psychotropic medications (e.g., anti-depressants, anxiolytics) as well as those used in medication assisted treatment (e.g., methadone, Suboxone). In addition, the use of pscyhedelics in the treatment of CODs is briefly explored. This section concludes with Chapter 8, which examines mindfulness as an adjunct treatment for CODs. The main mindfulness-based therapeutic programs are described, research studies supporting mindfulness are examined, and treatment integration ideas are offered"--