Objective: To examine the nature and conceptualization of generalized anxiety disorder (CAD) and chronic worry as well as data bearing on the validity of GAD as a distinct diagnosis. Method: Narrative literature review. Results: Although a wealth of data have been obtained on the epidemiology, genetics, and nature of GAD, many important questions remain regarding the validity of current conceptual models of pathological worry and the discriminability of GAD from certain emotional disorders (for instance, mood disorders) and higher-order trait vulnerability dimensions (for example, negative affect). Conclusion: Because the constituent features of GAD are salient to current conceptual models of emotional disorders (for example, models that implicate negative affect or worry/anxious apprehension as vulnerability factors), research on the nature of GAD and its associated features should provide important information on the pathogenesis, course, and cooccurrence of the entire range of anxiety and mood disorders.