To begin to resolve conflicts among current competing taxonomies of child and adolescent psychopathology, the authors developed an interview covering the symptoms of anxiety, depression, inattention, and disruptive behavior used in the Diagnostic and Statistical Manual of Mental Disorders (4th ed.; DSM-IV; American Psychiatric Association, 1994), the International Statistical Classification of Diseases and Related Health Problems (ICD-10; World Health Organization, 1992), and several implicit taxonomies. This interview will be used in the future to compare the internal and external validity of alternative taxonomies. To provide an informative framework for future hypothesis-testing studies, the authors used principal factor analysis to induce new testable hypotheses regarding the structure of this item pool in a representative sample of 1,358 children and adolescents ranging in age from 4 to 17 years. The resulting hypotheses differed from the DSM-IV, particularly in suggesting that some anxiety symptoms are part of the same syndrome as depression, whereas separation anxiety, fears, and compulsions constitute a separate anxiety dimension.