The medical physics workforce comprises approximately 24,000 workers worldwide and approximately 8,200 in the United States. The occupation is a recognized, established, and mature profession that is undergoing considerable growth and change, with many of these changes being driven by scientific, technical, and medical advances. Presently, the medical physics workforce is adequate to meet societal needs. However, data are emerging that suggest potential risks of shortages and other problems that could develop within a few years. Some of the governing factors are well established, such as the increasing number of incident cancers thereby increasing workload, while others, such as the future use of radiation treatments and changes in healthcare economic policies, are uncertain and make the future status of the workforce difficult to forecast beyond the next several years. This review examines some of the major factors that govern supply and demand for medical physicists, discusses published projections and their uncertainties, and presents other information that may help to inform short- and long-term planning of various aspects of the future workforce. It includes a description of the general characteristics of the workforce, including information on its size, educational attainment, certification, age distribution, etc. Because the supply of new workers is governed by educational and training pathways, graduate education, post-doctoral training, and residency training are reviewed, along with trends in state and federal support for research and education. Selected professional aspects of the field also are considered, including professional certification and compensation. We speculate on the future outlook of the workforce and provide recommendations regarding future actions pertaining to the future medical physics workforce.