Summary: In approximately 1200 words the entry reviews the development of the term from a slogan of political rhetoric to a scientific concept, summarizes elements of what constitutes a totalitarian regime, and refers to critics of totalitarianism theories. Early liberal attempts to understand the emergence of fascism in Italy(and later national- socialism in Germany) focused on the totality of the state as the main characteristic of these political movements. As the entry establishes, similarities to the developments in Bolshevik Russia were highlighted already in the 1920s by German Social Democrats which also focused on the totality of the state aspect. In that sense, totalitarianism was first used as political rhetoric by liberals and social democrats to defend the parliamentary democracy against both fascism and communism. A second strand of totalitarianism research was interested in the ideological and historical origins of totalitarianism, leading to Arend s classical comparative study of the elements and origins of totalitarian government in Italy, Germany and Russia, which the entry summarizes in parts. Another influential work the entry refers to is Friedrich and Brzezinski s project to develop an ideal type totalitarian regime. They identify a teleological encompassing ideology, a hierarchically organized one-man led party, a terror regime, a state news and weapons monopoly, and centralized control of the economy as key elements of a totalitarian state. The entry summarizes examples of empirical studies which increasingly questioned the closeness of the fit between the historical examples of totalitarian regimes and this ideal type model. Critics of totalitarianism theories have picked up on this fact and proposed theories of fascism instead. The entry argues at the end, that only further empirical studies based on both strands of theories will establish the respective usefulness.