A two-country, comparative static partial equilibrium model is used to simulate the ex ante market and welfare outcomes of U.S. country-of-origin labeling for the U.S.-Mexico fresh tomato trade. In all scenarios where consumers show a relative preference for U.S. tomatoes, Mexican tomato exports decline and U.S. production increases. Mexican trade losses using low- to mid-range consumer preference assumptions are 14% to 32% of the value of Mexican tomato exports to the United States and 1% to 3% of the total value of agricultural produce exports, partially negating the market access gains of NAFTA. Consumer effects are small and sometimes negative. Producer impact is the big effect, with transfer from Mexican to U.S. tomato producers.