The American Federation of State, County and Municipal Employees (AFSCME) is the second- or third-largest labor union in the United States and one of the fastest-growing, representing over 1.4 million employees, primarily in local and state government and in the health care industry. AFSCME is part of the AFL-CIO, one of the two main labor federations in the United States. Employees at the federal government level are primarily represented by other unions, such as the American Federation of Government Employees, with which AFSCME was once affiliated, and the National Treasury Employees Union; but AFSCME does represent some federal employees at the Federal Aviation Administration and the Library of Congress, among others.

According to their website, AFSCME organizes for social and economic rights of their protectorates in the workplace and through political action and legislative advocacy. It is divided into more than 3,500 local unions in 46 U.S. states, plus the District of Columbia and Puerto Rico. Each local union writes its own constitution, holds membership meetings, and elects its own officers. Councils are also a part of AFSCME's administrative structure, usually grouping together various locals in a geographic area.