Book excerpt: The American workforce is changing, creating new challenges for employers to provide occupational health services to meet the needs of employees. The National Aeronautics and Space Administration (NASA) workforce is highly skilled and competitive and employees frequently work under intense pressure to ensure mission success. The Office of the Chief Health and Medical Officer at NASA requested that the Institute of Medicine review its occupational health programs, assess employee awareness of and attitude toward those programs, recommend options for future worksite preventive health programs, and ways to evaluate their effectiveness. The committee's findings show that although NASA has a history of being forward-looking in designing and improving health and wellness programs, there is a need to move from a traditional occupational health model to an integrated, employee-centered program that could serve as a national model for both public and private employers to emulate and improve the health and performance of their workforces.