This chapter reviews the convergent, discriminant, criterion, and incremental validity of symptoms of the DSM-5 anxiety disorders; these include panic disorder, agoraphobia, social anxiety disorder/social phobia, specific phobia, and generalized anxiety disorder (GAD). Symptom measures of social anxiety/social phobia, panic disorder, claustrophobia, and GAD generally displayed impressive construct validity in these data. Specifically, they tended to show strong convergent validity and significant discriminant validity across both self-report and interview-based measures; moreover, they displayed substantial criterion validity and impressive incremental validity in relation to conceptually linked DSM diagnoses. One problem, however, is that they generally showed poor diagnostic specificity; that is, although they correlated substantially with their target diagnoses, they often displayed equally strong relations with at least some other internalizing disorders. In contrast, self-report measures of agoraphobia and specific phobia (particularly the latter) generally exhibited unimpressive criterion and incremental validity in these analyses.