In the period after WWI workers' revolutions swept Europe, but failed to seize power and destroy capitalism. In this context fascism emerged- a new kind of counter-revolutionary movement based on mass mobilisation, extreme nationalism and demagogic anti-capitalist rhetoric. Understanding this new phenomenon was a challenge for the Communist International, and provoked a series of debates which generated some important insights about the nature of fascism and how to fight it. But the Communist movement also failed to stop the rise of Hitler and Mussolini. This session will explore the Communist response to the rise of fascism and attempt to explain why they ultimately failed to confront it.