Received June 20, 2002; revision received March 27, 2003; accepted April 7, 2003. From the National Institute of Mental Health Collaborative Program on the Psychobiology of Depression—Clinical Studies; the Department of Psychiatry and Human Behavior, Brown University, Providence, R.I.; the Department of Psychiatry, Cornell University, New York; the Department of Research and Training, New York State Psychiatric Institute, New York; and the Department of Psychiatry, University of Iowa, Iowa City. Address correspondence to Dr. Solomon, Mood Disorders Program, Department of Psychiatry, Rhode Island Hospital, 593 Eddy St., Providence, RI 02903-4970; DASolomon@Lifespan.org (e-mail). The National Institute of Mental Health Collaborative Program on the Psychobiology of Depression—Clinical Studies is conducted with the participation of the following investigators: M.B. Keller, M.D. (Chairperson, Providence, RI); W. Coryell, M.D. (Co-Chairperson, Iowa City, IA); T.I. Mueller, M.D., D.A. Solomon, M.D. (Providence, RI); J. Fawcett, M.D., W.A. Scheftner, M.D. (Chicago); J. Haley (Iowa City, IA); J. Endicott, Ph.D., A.C. Leon, Ph.D., J. Loth, M.S.W. (New York); and J. Rice, Ph.D., T. Reich, M.D. (St. Louis). Other contributors include H.S. Akiskal, M.D., N.C. Andreasen, M.D., Ph.D., P.J. Clayton, M.D., J. Croughan, M.D., R.M.A. Hirschfeld, M.D., L. Judd, M.D., M.M. Katz, Ph.D., P.W. Lavori, Ph.D., J.D. Maser, Ph.D., M.T. Shea, Ph.D., R.L. Spitzer, M.D., and M.A. Young, Ph.D. Deceased: G.L. Klerman, M.D., E. Robins, M.D., R.W. Shapiro, M.D., and G. Winokur, M.D. This manuscript has been reviewed by the Publication Committee of the Collaborative Depression Study and has its endorsement.