Generalized anxiety disorder (GAD) and major depression (MD) form the largest group of common mental disorders. These two conditions often occur together, and emerging evidence suggests several similarities between them. As we move toward revising the Diagnostic and Statistical Manual of Mental Disorders for DSM-V, Diagnostic Issues in Depression and Generalized Anxiety Disorder: Refining the Research Agenda for DSM-V explores the nosologic relationship between GAD and MD. This book acts as a guidepost for the entire DSM process. It reviews recent scientific advances in our understanding of the interrelationship between GAD and MD, summarizes the body of evidence into a few broad conclusions, and reflects on the implications of these findings for future nosologic efforts. The contributing authors review conceptual issues and empirical data from a variety of perspectives, including genetics, biology, treatment, development, course, predictors, disability, and psychosocial stressors. Diagnostic Issues in Depression and Generalized Anxiety Disorder develops operationalized criteria for nosologic decisions that enable clinicians to bridge the gap between data and diagnostic recommendations. Not only does the methodology of investigating an active interchange between empirical and conceptual perspectives shed new light on the relationship between GAD and MD, but it also carries implications for the rest of DSM-V.