Received July 28, 2004; revisions received Oct. 28, 2004, and Jan. 12, 2005; accepted Feb. 14, 2005. From the RAND Corporation and the UCLA/NPI Health Services Research Center, Los Angeles. Address correspondence and reprint requests to Dr. Watkins, RAND Corporation, 1776 Main St., P.O. Box 2138, Santa Monica, CA 90407-2138. This work was supported by the RAND Health Program (Drs. Watkins and Paddock), NIMH grant R01 MH-61570, and UCLA Center Grant P30 MH-068639 (Dr. Wells and Ms. Zhang). The authors thank Maureen Carney, M.S., for coordination of Partners in Care follow-up; Barbara Levitan, B.A., for oversight of the survey work; Bernadette Benjamin, M.S., for programming support; and Naihua Duan, Ph.D., and Lingqi Tang, Ph.D., for statistical consultation. The authors also thank the clinicians and patients who contributed their time and efforts to this study. The following managed care organizations and their associated behavioral health organizations participated in the Partners in Care trial: Allina Medical Group (Twin Cities, Minn.), Patuxent Medical Group (Patuxent, Md.), Humana Health Care Plans (San Antonio, Tex.), MedPartners (Los Angeles), PacifiCare of Texas (San Antonio), Valley-Wide Health Services (Alamosa, Colo.), Alamo Mental Health Group (San Antonio, Tex.), San Luis Valley Mental Health/Colorado Health Networks (Alamosa, Colo.), and Magellan/GreenSpring Behavioral Health (Patuxent, Md.).