The impending retirement of baby-boomers in the U.S. and the ever-increasing life expectancy there and throughout the world have generated interest in how much older citizens contribute to production. Through a review of social science literature and an analysis of Census, Bureau of Labor Statistics, and other data, this paper explores how older persons in the U.S. allocate their time to different types of productive activities, and identifies the incentives and disincentives that influence this allocation. The paper is written mainly from an economic perspective, but main themes found in sociology and psychology are used to consider obstacles, predisposing factors, and incentives to productive activities. Both paid and unpaid productive activities are analyzed. The main findings are: (1) Older Americans are employed in a wide variety of occupations and industries. (2) Nontraditional employment arrangements such as independent contractors, home-based work, part-time work, and bridge jobs are important to older workers, but opportunities for these activities may be limited. (3) Unpaid volunteer work in organizations such as schools and churches, and informal help given to family and friends, are part of older persons' contribution to society. (4) Economic, psychological, and sociological factors influence the level of productive activities of older persons, and are manifest in the decision-making of both employers and employees. (5) While recent changes in public policy such as modifications to the social security system may be conducive to the continuing labor force participation of workers nearing retirement age, there may be room for more proactive measures.