The American Conservative Union (ACU) is an American political organization that advocates for conservative policies, ranks politicians based on their level of conservatism, and organizes the Conservative Political Action Conference. Founded on December 18, 1964, it calls itself the oldest ongoing conservative lobbying organization in the U.S. The ACU is concerned with issues such as personal liberty or freedom, and traditional values, which they define as foundations of conservatism.

The Conservative Political Action Conference is an annual political conference attended by conservative activists and elected officials from across the United States. CPAC is hosted by the American Conservative Union (ACU). The first CPAC took place in 1974.