International disputes over subsidies are increasingly disrupting the world trading system. The creation of the WTO was nearly prevented by disputes in the Uruguay Round of GATT negotiations over the issue of negotiating disciplines on agricultural subsidies, an issue which continues to plague the ongoing Doha Round of WTO negotiations. Ongoing disputes over subsidies that violate existing WTO rules have led to the largest amount of authorized retaliation in GATT/WTO history. Yet the international rules that govern subsidies have received little attention in the form of systematic economic analysis. In this paper we provide a first formal analysis of the international rules that govern the use of subsidies to domestic production (as distinct from export subsidies). Our analysis highlights the impact of the new disciplines on subsidies that were added to GATT rules with the creation of the WTO. Our results suggest that, although GATT subsidy rules were typically viewed as weak and inadequate while the WTO subsidy rules are seen as representing a significant strengthening of multilateral disciplines on subsidies, the key changes introduced by the WTO subsidy rules may ultimately do more harm than good to the multilateral trading system, by undermining the ability of tariff negotiations to serve as the mechanism for expanding market access to more efficient levels.