Recent advances in basic and clinical research in the anxiety disorders converge on several areas: (1) critical distinguishing clinical features of these disorders, (2) the neurobiological basis of anxiety disorders in human populations, (3) animal studies that defi ne cause-effect relations between neural function and anxiety or fear behaviors, and (4) studies of etiology that provide an increasingly clear understanding of the developmental trajectories that defi ne vulnerability for anxiety disorders. Additionally, an emerging area of research is studies of behavior, cognitive function, and neural activity in clinical populations to defi ne the clinically relevant effects of pharmacological and psychotherapeutic treatments. This chapter summarizes and synthesizes current research approaches to anxiety disorders and attempts to show the impact of this research on current trends in their diagnosis and treatment. Currently, there is increasing emphasis on relevant clinical dimensions, as opposed to more traditional categorical approaches, and an emerging view of anxiety as a set of cognitive-perceptual disorders that derives from alterations in neural systems critical for attentional processes and emotional regulation. Phillips K , Fulker DW , and Rose RJ ( 1987 ) Path analysis of seven fear factors in adult twin and sibling pairs and their parents . Genetic Epidemiology 4 , 345 -355 .