Sanitary and phytosanitary (S&P) regulations that protect both U.S. and Mexican agriculture and consumers from exotic pests and diseases and other foodborne contamination (such as pesticide residues) will continue to be effective under the North American Free Trade Agreement (NAFTA). The presence of pests and diseases limits the movement of food and agricultural products between the United States and Mexico. Even with S&P measures in place, the risk of cross-border contamination continues because pests and diseases do not recognize national borders. The previous cooperative efforts between the United States and Mexico to prevent and control infestation and infection will likely continue regardless of the reduction or removal of trade-restricting measures. Both countries, however, desire to prevent the simultaneous proliferation of new S&P measures that might substitute for tariffs or quotas.