This article reconstructs the economic expertise of the Italian Communist Party and the French Communist Party from the second post-War period to the 1950s. It analyses the workings of the Parties' internal and external structures in charge of economic studies and their cultural currents, and studies the role of economists and economic experts, their sociological profile, and their militancy and status in the communist partisan organization. The study shows the presence of a common economic culture in French and Italian communism during the period. Some differences bear highlighting: the more intellectual profile of the Italian communist leadership group, and a different relationship between Party and intellectuals; the importance of trade-union economic expertise and a greater influence of Soviet economic literature in the Fcp.