This chapter is devoted to the developments of economic thought in France between 1870 and the First World War. After several decades of institutional and intellectual dominance, liberal thinking is on the wane and is being challenged from many sides. The creation of new academic journals, and the expansion of political economy in French universities largely benefits to a new generation of economists who are open to protectionist and social ideas, and turned towards empiricism and history. Charles Gide (1847–1932), Paul Cauwès (1843–1917), Clément Juglar (1819–1905) and Albert Aftalion (1874–1956), among others, embody these new insights. The chapter concludes with a presentation of the decisive contributions to economic analysis of some engineers-economists – Clément Colson, Marcel Lenoir, Maurice Potron - and mathematicians – Joseph Bertrand, Louis Bachelier - over the period.