1. Department of Psychiatry and Human Behavior, Warren Alpert Medical School of Brown University, and Pediatric Anxiety Research Center, Bradley Hospital, Riverside, R.I. (Gold); Emotion and Development Branch, NIMH, Bethesda, Md. (Abend, Behrens, Farber, Ronkin, Leibenluft, Pine); Department of Psychology, University of Miami, Coral Gables, Fla. (Britton); Scientific and Statistical Computing Core, NIMH, Bethesda, Md. (Chen).