This article examines the interchangeability of paid and volunteer labor. It reports on estimates and prevalence of such interchangeability through a series of studies of Canadian nonprofits: two national surveys of nonprofit organizations and case studies of two hospitals. The first study found evidence that volunteers were replacing paid staff and that paid staff were replacing volunteers, sometimes in the same organization. The second study explored this pattern further and found the percentage of tasks that were interchangeable. The third study found that about two-thirds of the organizations in the sample agreed that the interchangeability of tasks occurred, but the data indicated that it was limited to about 12% of tasks, not dissimilar to the estimates from the case studies. The implications of the results are discussed, and a model for the interchangeability of paid and volunteer labor is presented.