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.

Frank Straus Meyer was an American philosopher and political activist best known for his theory of "fusionism" – a political philosophy that unites elements of libertarianism and traditionalism into a philosophical synthesis which is posited as the definition of modern American conservatism. Meyer's philosophy was presented in two books, primarily In Defense of Freedom: A Conservative Credo (1962) and also in a collection of his essays, The Conservative Mainstream (1969). Fusionism has been summed up by E. J. Dionne, Jr. as "utilizing libertarian means in a conservative society for traditionalist ends."