The Mexico-U.S. border environmental situation is outlined in this note which provides background information on the region. The nature and extent of the pollution problem and a brief overview of the current system of environmental regulation and enforcement in Mexico and under the North American Free Trade Agreement is also reviewed. The note also provides two caselets of companies operating in the border region. The principle objective of this note is to familiarize students with some of the major debates surrounding the relationship between globalization (expansion of international trade and investment) and the natural environment. It offers the chance for students to learn about the Mexican-U.S. border situation and to consider both the causes of and possible solutions to the serious and complex pollution problem in the region.