We characterize the optimal tariff bindings in a trade agreement among asymmetric countries that are subject to idiosyncratic political-economy shocks. We find that the optimal tariff binding is decreasing in the relative size of the importing country and its degree of comparative disadvantage. Moreover, under an optimal agreement a smaller country is more likely to apply a tariff that is substantially below its tariff binding. Using applied and bound tariff data from WTO member countries, we …nd strong empirical support for our predictions.