on a special topic, for example, on testing and treatment for opioid use disorder in state and federal prisons. The NPS and NCRP are BJS’s flagship data collections measuring the size and composition of state and federal prison populations on an annual basis. The two collections complement each other by obtaining aggregate and detailed individual-level information on prisoners, which is used to describe and compare the prison population over time. The NPS collects aggregate counts of the male and female custody and jurisdictional prison populations as of December 31 each year. State departments of corrections (DOCs) and the Federal Bureau of Prisons (FBOP) use administrative records to tally their prison populations by jurisdiction, types of prison admissions and releases during the past year, race/Hispanic origin, and capacity of the facilities that hold prisoners in their custody. The NPS also provides annual information on the number of confirmed cases of HIV/AIDS and current testing policies for these conditions. The NPS has been collected annually since 1926, and data are used in BJS’s Prisoners series and Corrections Populations in the United States series bulletins.