Because of their high prevalence and their negative long-term consequences, child anxiety disorders have become an important focus of interest. Whether pathological anxiety and normal fear are similar processes continues to be controversial. Comparative studies of child anxiety disorders are scarce, but there is some support for the current classification of anxiety disorders in children and adolescents, except for generalized anxiety disorder. The greatly differing rates of anxiety disorders in child population studies, and of specific disorders in clinical samples, inconsistent findings regarding course, and disparate placebo response rates all suggest a need for more precise, validated, criteria for symptoms, distress, and impairment. Several treatments have documented efficacy, and promising prevention efforts are encouraging.