Acknowledgment: We thank Joan Buttenfield, BSN, who coordinated the study, and Sandra O’Donnell, RN, who coordinated the Depression and Manic Depression Prevention Program in which the study was carried out. We thank Debra Frankel, ACSW; Steve Carter, PhD; Gay Herrington, PhD; Kathy Reilly, PhD; Lee Wolfson, MEd, PhD; Lyn Silberman, MSW; Paula Moreci, MSW; Kelly Wells, MSW; and Sue Morris, MSW, all of whom provided the interpersonal and social rhythm therapy and intensive clinical management to study participants. We thank David Averbach, MD; Daniel Cole, MD; Ed Friedman, MD; Eric Nofzinger, MD; Eydie Moses, MD; Fouzia Laghrissi-Thode, MD; Jair Soares, MD; Joshua McDavid, MD; Katalin Szanto, MD; Margaret Fitzgerald, MD; Shakeel Ahmed, MD; William Musser, MD; and Wayne Drevets, MD, all of whom provided the pharmacologic management of the study participants. We thank Charles F. Reynolds, III, MD; Mark Miller, MD; Samuel Gershon, MD; Ihsan Salloum, MD; and Cleon Cornes, MD, who performed the recurrence evaluations. We thank Tracilynn Salopek, MSW; Dana Fleming, RN, MSW; John Keil, MSW; Steve Verfaille, MSW; and Margie Knorr, RN, who performed the study evaluations. We thank Deborah Stapf, BS, and Gail Kepple, BA, who were responsible for data management, and Dorothy Wilson, MD; Lori Siegel, PhD; and Bryan Kostelnik, BA, who conducted the Life Charting interviews. We thank Randi Taylor, PhD, for supervising the fidelity monitoring; Joel Greenhouse, PhD, for ongoing consultation throughout the development and conduct of the study and the analysis of results; Cindy Ehlers for her work on the development of the social zeitgeber hypothesis; and other contributors whom we were not able to contact.