The United States Agency for International Development (USAID) is a statutory agency of the executive branch of the United States federal government. Founded in 1961, it was formerly the world's largest foreign aid agency, but it received major cutbacks in 2025 with its remaining functions being transferred to the United States Department of State. and the agency is due to close its doors by September 2026. the Office of Inspector General, and court filings have continued to acknowledge USAID's legal existence.
USAID's predecessor agency was already substantial, with 6,400 U.S. staff in developing-country field missions in 1961. Except for the peak years of the Vietnam War, 1965–70, that was more U.S. field staff than USAID would have in the future, and triple the number USAID has had in field missions in the years since 2000.