In addition to reconstructing Pareto’s biography, this chapter is dedicated to the principal studies he conducted prior to the publication of the Treatise. Pareto’s early writings, which focus mainly on the problems faced by post-unification Italy, display his clear liberal imprint. They were followed by his major works on economics—the Cours d’économie politique and the Manuale di economia politica—written after his appointment as professor of political economy at the University of Lausanne. Pareto’s growing interest in sociological issues eventually led him to devote himself almost exclusively to the study of these matters. However, we certainly cannot conclude from this that he went through two distinct phases—one purely economic and the other eminently socio-political.