We develop a framework to incorporate exchange rates into a differential demand system and apply it to U.S. demand for fresh tomatoes by country of origin. We find evidence of incomplete exchange-rate pass-through involving Mexico. Results indicate that accusations of dumping by American agricultural groups in 1995–1996 coincide with the appreciation of the U.S. dollar against the peso in 1994–1995. Traditional modeling approaches that do not account for exchangerate effects would not capture the distinction between dumping and changes in relative prices, leading to the conclusion that too many tomatoes were being imported from Mexico.