A biological-environmental interaction currently provides the best explanation of an anxiety disorder's evolution. In this sense, anxiety disorders are like other medical disorders for which a person may have a predisposition. Our knowledge of the evolution of anxiety disorders would be enhanced by the ability to identify those persons predisposed to anxiety and to identify such "proneness" before an anxiety disorder emerges in adulthood. We discuss the developmental aspects of panic disorder and social phobia, in particular findings suggesting that behavioral inhibition in children may be a precursor to phobic disorders in adults. Only longitudinal studies will resolve whether childhood response patterns are specifically linked to the risk of developing anxiety disorders or other psychopathology across the life cycle. In the interim, we suggest some guidelines for parents and clinicians to meet the unique needs of the inhibited child.