Despite the wide range of publications about Julio Cortázar, there is no study that specifically addresses the question: what does Cortázar mean by 'el hombre nuevo'? Based on a careful reading of two of his novels, Rayuela / Hopscotch and Libro de Manuel / A Manual for Manuel, my thesis defines 'el hombre nuevo' as Cortázar's attempt to establish a dialogue with the reader in order to invent together a new understanding of the human being. 'El hombre nuevo' involves an extended ontological search which is continued outside of the text, and the relationship author-reader goes beyond a dyadic model into the construction of a new community of new men and new women.