Does WTO Matter for the Extensive and the Intensive Margins of Trade?

We use 6-digit bilateral trade data to document the effect of WTO/GATT membership on the extensive and intensive product margins of trade. We construct gravity equations for the two product margins where the specifications of these gravity equations are motivated by the model of Eaton and Kortum (2002). The data show that the puzzle of no significant impact of WTO membership on trade documented by Rose (2004) manifests itself differently at the product margins of trade. We show that the impact of the WTO is almost exclusively on the extensive product margin of trade, i.e. trade in goods that were not previously traded. In our preferred specification, WTO membership increases the extensive margin of exports by 31%. At the same time, WTO membership has a negligible or even a negative impact on the intensive margin (the volume of already-traded goods). Incidentally, we also document that standard gravity variables provide good explanatory power for bilateral trade on both margins.