The paper explores the possibility of philosophical cooperation between Thomism and American Pragmatism by resurrecting a largely forgotten debate between Wilmon Henry Sheldon and Jacques Maritain. The discussion focuses primarily on two topics: the compatibility between a substance ontology and a pragmatist-evolutionary ontology, and the compatibility between the scholastic and the pragmatist theories of truth. The paper claims that, if we bring Peirce's version of pragmatism into the picture, cooperation is not only possible but likely to be fruitful.