The authors thank Rutgers Cell and DNA Repository for extracting DNA and providing samples. The STEP-BD project was funded in whole or in part with Federal funds from the National Institute of Mental Health (NIMH), National Institutes of Health, under contract N01MH-80001 to Gary S. Sachs, M.D. (principal investigator), Michael E. Thase, M.D. (co-principal investigator), and Mark S. Bauer, M.D. (co-principal investigator). Active STEP-BD sites and principal investigators included: Baylor College of Medicine (Lauren B. Marangell, M.D.); Case University (Joseph R. Calabrese, M.D.); Massachusetts General Hospital and Harvard Medical School (Andrew A. Nierenberg, M.D.); Portland VA Medical Center (Peter Hauser, M.D.); Stanford University School of Medicine (Terence A. Ketter, M.D.); University of Colorado Health Sciences Center (Marshall Thomas, M.D.); University of Massachusetts Medical Center (Jayendra Patel, M.D.); University of Oklahoma College of Medicine (Mark D. Fossey, M.D.); University of Pennsylvania Medical Center (Laszlo Gyulai, M.D.); University of Pittsburgh Western Psychiatric Institute and Clinic (Michael E. Thase, M.D.); and University of Texas Health Science Center at San Antonio (Charles L. Bowden, M.D.). Collection of DNA from consenting participants in STEP-BD was supported by N01-MH-80001 (Gary S. Sachs, M.D., principal investigator). The Sequenced Treatment Alternatives to Relieve Depression (STAR*D) study was supported by federal funds from NIMH under contract N01 MH-90003 to the University of Texas Southwestern Medical Center at Dallas (A. John Rush, M.D., principal investigator). Genotyping of STAR*D samples was funded by NIMH (R01 MH-072802; Steven P. Hamilton, M.D., Ph.D., principal investigator).The CATIE project was funded by NIMH contract N01 MH-90001. Control subjects from the NIMH Schizophrenia Genetics Initiative (NIMH-GI) data and bio-materials were gathered by the Molecular Genetics of Schizophrenia II (MGS-2) collaboration. The investigators and co-investigators are: Evanston Northwestern Healthcare/Northwestern University, Evanston, Ill., MH-059571, Pablo V. Gejman, M.D. (collaboration coordinator; principal investigator), Alan R. Sanders, M.D.; Emory University School of Medicine, Atlanta, MH-59587, Farooq Amin, M.D. (principal investigator); Louisiana State University Health Sciences Center, New Orleans, MH-067257, Nancy Buccola A.P.R.N., B.C., M.S.N. (principal investigator); University of California-Irvine, Irvine, Calif., MH-60870, William Byerley, M.D. (principal investigator); Washington University, St. Louis, Mo., U01 MH-060879, C. Robert Cloninger, M.D. (principal investigator); University of Iowa, Iowa City, IA, MH-59566, Raymond Crowe, M.D. (principal investigator), Donald Black, M.D.; University of Colorado, Denver, Colo., MH-059565, Robert Freedman, M.D. (principal investigator); University of Pennsylvania, Philadelphia, MH-061675, Douglas Levinson, M.D. (principal investigator); University of Queensland, Queensland, Australia, MH-059588, Bryan Mowry, M.D. (principal investigator); Mt. Sinai School of Medicine, New York, MH-59586, Jeremy Silverman, Ph.D. (principal investigator).