National Institute of Mental Health, National Institutes of Health, Bethesda, Md: Ellen Stover, PhD; Stephen H. Koslow, PhD (co-project directors); Benedetto Vitiello, MD (medical officer); Walter L. Goldschmidts, PhD (study coordinator); Loretta E. Grau, PhD (study assistant). University of Southern California, Los Angeles: Peter N. R. Heseltine, MD (principal investigator); Elaine M. Eaton, PhD (coinvestigator, neuropsychology); Eugene Sobel, PhD (coinvestigator, statistics); Lon Schneider, MD; Michael McGrail, MD (psychiatry); Cynthia Lieu, RPharm (pharmacy); Stephen Whipple, PhD (research associate); Adrian Brenn (research assistant); Zhiming Li (data manager). University of California, San Diego: J. Hampton Atkinson, MD (principal investigator); Robert K. Heaton, PhD (coinvestigator, neuropsychology); Stephen Brown, MD (study manager); Ki Song (data manager). University of Miami, Miami, Fla: Karl Goodkin, MD, PhD (principal investigator); Frances L. Wilkie, PhD (coinvestigator, neuropsychology); Dan Feaster (data manager). Cosmos Corp, Data Coordinating Center, Bethesda, Md: Darryl Crompton, JD (project director); Darci Terrell (associate administrator); Robert Shaw (project assistant). George Washington University Biostatistics Center, Statistical Analysis Center, Rockville, Md (subcontract NO-8-94-010): James Rochon, PhD (associate research professor, statistics); Raymond Bain, PhD (research professor, statistics); Samuel Greenhouse (professor emeritus, statistics); Shu-Ping Lan (research scientist).