This book provides the latest theory and research on the critical connection between depression and insomnia for scientist-practitioners and practitioner-scholars, alike. It equips the reader with specific recommendations for conceptualizing, assessing, and treating depression and insomnia, and related issues in therapy. Part I of the book focuses on the depression-insomnia link and highlights relevant processes, such as difficulty with anticipating or pursuing rewards, rumination and worry, and stress and affect dysregulation. Part II of the book reviews existing cognitive behavioral interventions for depression and insomnia, including cognitive behavioral therapy for depression, cognitive behavioral therapy for insomnia, mindfulness-based therapies, and acceptance and commitment therapy, as well as how they may be used, modified, and delivered to treat these problems. Finally, Part III reviews application of the science and clinical practice recommendations to several special populations, including college students and emerging adults, older adults, individuals with comorbid psychiatric disorders, and individuals experiencing medical illness. Investigators, students, and practicing professionals will find this cutting-edge presentation an invaluable resource for issues that are common occurrences in psychotherapy.