Homelessness is associated with a multitude of poor health outcomes. However, the full extent of the risks associated with homelessness is not possible to quantify without reliable population data. Here, we outline 3 federal, publicly available data sources for estimating the number of people experiencing homelessness in the United States. We describe the appropriate uses and limitations of each data source in the context of infectious disease epidemiology. These data sources provide an opportunity to expand current research and develop actionable analyses.