Although higher rates of substance use among young adults aged 16 to 24 are well-established (OAS, 2010), existing workplace substance use prevention and early intervention programs primarily target older workers. These data suggest that workplaces need substance abuse prevention and early intervention programs that are proven to be efficacious with young working adults. To address this critical need in American workplaces, in 2004 the Substance Abuse and Mental Health Services Administration (SAMHSA) announced its Young Adults in the Workplace initiative (originally entitled Youth in the Workplace [YIW]) (SAMHSA, 2004). The YIW initiative was designed as a two-phase collaborative effort among SAMHSA investigators, multiple grantees, and a coordinating center. It was conceived as a mechanism to test the efficacy of workplace substance use prevention or early intervention programs for young working adults aged 16 to 24. In Phase I, SAMHSA required grantees to develop workplace programs by starting with interventions shown to be efficacious either for adults in workplace settings or for young adults in non-workplace settings and to modify these programs specifically for use with young adult workers. In Phase II, SAMHSA funded a subset of the Phase I grantees to implement the workplace programs and to participate in a cross-site evaluation of the YIW initiative conducted by the Coordinating Center. Based on a peer-review process, SAMHSA funded 13 Phase I grantees and 6 Phase II grantee teams (including workplace partners). This publication briefly describes the background and rationale for the YIW initiative, presents the interventions implemented by the six YIW grantees, and provides an overview of the methods and design of the cross-site evaluation. Chapters in this book include: (1) The Young Adults in the Workplace Initiative: An Introduction (Deborah M. Galvin, William Schlenger, and Johannes Norling); (2) Healthy WorkLife for Young Adults: Implementing Health Promotion and Substance Abuse Prevention in a Health Care Setting (Rebekah K. Hersch, Royer F. Cook, Daniel Hughes, Samantha L. Leaf, and Douglas W. Billings); (3) Substance Abuse Prevention for the Young Workforce in the Railroad Industry: An Adaptation of the PREVENT Program (Rebecca Spicer, Ted Miller, and Eduard Zaloshnja); (4) Team Resilience: Health Promotion for Young Restaurant Workers (Joel B. Bennett and Charles C. Aden); (5) Substance Abuse Prevention in the Electrical Industry: The NECA-IBEW Team Awareness and Team Vigilance Programs (Eric Einspruch, Chris O'Neill, Kelly Jarvis, Kelly Vander Ley, and Pamela Raya-Carlton); (6) Adapted Team Awareness for Youth and Conservation Corps (Jean Denious, Chandra Ring, Nick Reese, Jennifer Hooks, Caitlin Kozicki, Cori Stott, and Brie Reimann); (7) LifeSkills Training Wellness Program: An Application for Young Adults in Supermarkets (Christopher Williams, Jessica Samuolis, Kenneth W. Griffin, and Gilbert J. Botvin); and (8) The Young Adults in the Workplace Initiative: Cross-Site Evaluation Methods (Georgia T. Karuntzos, Jeremy Bray, Laurie Cluff, and Deborah M. Galvin). Chapters contain figures, tables and references.