The subject suggested in the title is so broad as to make it rather difficult to decide what boundaries to draw around the study of various resources available to the historian or other social scientist who sets out to study labor history, the social history of Italian workers and peasants, and the political and intellectual history of socialism and other radical movements. Keeping in mind that the following discussion is not intended to be exhaustive, but rather an indication of the necessary starting point to begin an investigation is probably the best way to understand this note.

The Feltrinelli Institute was founded in 1949 by the Milanese publisher Giangiacomo Feltrinelli – its aim “to promote the knowledge and study – carried out in accordance with strictly scientific criteria and complete ideological autonomy – of the history, the political and economic thought and the social ideas of the modern and contemporary eras; particular importance is to be given to Italy and to the economic phenomena, political doctrines and more historically important social movements of the country.” Feltrinelli's initiative, which began with the library and a rich collection of materials on French socialism, was an important first step toward filling the vacuum in documentation and research on the Italian working class and socialist movements left by two decades of Fascist government. In the following years, the library and research activities of the Institute played a leading role in the reconstruction of intellectual life and political debate in Italy. Its publications, especially Movimento Operaio (1947–1955) and the Annali (1958-) contained some of the most important contributions to the study of the Italian working class and peasantry, and socialist movements made in the postwar period.