This paper investigates the influence that changes in incentives to retire will have on people's participation in volunteer activities. The first section presents background information on the extent of volunteerism in the United States. It reports that about one out of every five men aged 57 to 71 did some volunteer work in 1978 and about one out of every four women aged 42 to 56 did some volunteer work in 1979. Information on federally sponsored ACTION programs for older Americans indicates that about one percent of the population 60 years and older volunteers in these ways. Section 2 provides a conceptual basis for empirically testing who volunteers and why. Section 3 presents these empirical findings: education has a positive influence, areas with concentrations of people in need do not necessarily have the greatest number of volunteers, a history of volunteering strongly predicts current participation, and retirement policies concerning the amount of time people work and the amount of income may affect men's and women's volunteerism in different ways. Conclusions and policy implications are presented in section 4. (An appendix describes the empirical model of volunteerism and its results and provides six data tables.) (YLB)