In view of the demise of "actually existing socialism", renowned researchers from Germany and France take stock of the emergence, development and current significance of communist ideologies. Marxism, Leninism, Trotskyism, Luxemburgism, Gramscism and the "New Left" are questioned and critically examined from the perspective of the democratic constitutional state on totalitarian tendencies. From the content: S. Courtois: Communism in the Age of Totalitarianism - K. Lw: The "dictatorship of the proletariat". Karl Marx - D. Colas: Lenin and Leninism - E. Jesse: Democracy or dictatorship? Luxemburgism - C. Bourseiller: Trotsky and Trotskyism - P. Moreau: Gramsci and Gramscism - G. Koenen: The New Left of 1968 - W. Mller: Was there a democratic communism in Germany? - U. Backes: Totalitarian Thinking.