LGBTQ individuals seek therapy at higher rates than the general population, but the mental health profession has historically lacked evidence-based guidance for supporting the unique presenting concerns of LGBTQ clients. This book changes that by presenting how-to guidance for delivering cognitive-behavioral therapy that directly responds to the distinct stressors facing LGBTQ individuals. LGBTQ-affirmative Cognitive-Behavioral Therapy is the first mental health treatment designed by and for LGBTQ individuals that has been tested in several randomized controlled trials with diverse segments of the LGBTQ community. Results of these trials show that this transdiagnostic treatment is associated with reductions in depression, anxiety, substance use problems, and psychological distress, making it suitable for a broad range of presenting concerns. LGBTQ-affirmative Cognitive-Behavioral Therapy: Therapist Guide teaches the principles and techniques that mental health practitioners can use to affirmatively respond to the distinct stressors that their LGBTQ clients often face. The book follows a clear step-by-step approach with nine modules, each of which teaches skills for enhancing LGBTQ clients' mental well-being by undoing the deep impact that early and ongoing LGBTQ-related stress can have on basic psychological processes. This Therapist Guide is intended to be accompanied by the Client Workbook, which contains accessible, step-by-step guidance and worksheets for clients to follow when participating in this treatment. This guide provides essential tools for helping therapists effectively and affirmatively respond to the unique needs of their LGBTQ clients.