Between August 1846 and April 1847, Guiseppe Mazzini, in London exile, published six articles in English in the People’s Journal, the last of which was on Communism. With these articles, which became known in his native country in an 1852 Italian reworking, Mazzini powerfully inserted himself into the debate on the nature of democracy, alongside the most illustrious intellectuals of the time, Tocqueville, Blanc, Cabet, and Proudon. In two of his pieces, Mazzini answered the democratic communists-the Fraternal Democrats-who in 1847 invited the twenty-eight year old Karl Marx to London to rebut Mazzini’s perceptive criticisms of communism and to explore a new possible elaboration of the ideology. Mastellone confronts the English text of Mazzini with the German text of Marx and traces an almost forgotten theoretical contest that has been ignored, but remains crucial for an understanding of two fundamental movements of the modern world: communism and democracy.