The text reconstructs the studies carried out by Mario Dal Pra on the philosophy of Karl Marx between the middle of the 1950s and the beginning of the 1960s. It insists on the relationship existing between the interpretation of historical materialism and the theoretical debates on historiography. During these debates, Dal Pra came very close to Giulio Preti’s position, because the latter advanced a reading of historical materialism that was epistemological rather than political or moral and, as such, capable of solving the problems of philosophical historiography. The results achieved by Preti convinced Dal Pra and caused him to reconsider his previous position. Once re-connected in an epistemological key to reflections on historiography, Marx’s philosophy opened the way to critical historicism. In the following years (1960-68), ‘praxis’ and ‘materialistic epistemology’ would be rebalanced through the investigation of dialectics in the Marxian works written before Capital.