The Cobden-Chevalier treaty of 1860 eliminated French import prohibitions and lowered tariffs between France and Great Britain. The policy change was largely unexpected and unusually free from direct lobbying. A series of commercial treaties with other nations followed. Post-1860, we find a significant rise in French intra-industry trade. Sectors that liberalized more experienced higher two-way trade. Our findings are consistent with the idea that trade liberalization led to smooth adjustment that avoided costly inter-sectoral re-allocations of factors.