The debate over acid rain in North America has produced an interesting set of political interactions within the United States and between Canada and the U.S. at the subnational level. The long delay in reaching a bilateral agreement coupled with congressional inaction has stimulated relations at the subnational level between the two countries. This article will investigate the role of provinces and states in foreign policy-making and the agreements that have occurred. This type of activity - known as paradiplomacy - has been the subject of research in both North America and Europe in recent years by a number of political scientists (Duchacek 1986, Soldatos 1986). The focus for the analysis to follow is the nonbinding agreement - the Memorandum of Understanding. To date, eight Memoranda either entirely or in part devoted to acid rain have been signed by states and provinces. The first was signed by New York and Quebec in 1982 and the most recent was an expanded agreement signed by New York and Quebec in 1986. Other agreements include New York and Ontario (1983), Minnesota and Ontario (1983), a New York and Quebec Amendment to the 1982 Agreement (1984), Michigan and Ontario (1985), British Columbia and Washington State (1985), and Wisconsin and Quebec (1985). It is important to review briefly the politics of acid rain in order to understand the context for the subnational agreements. After this overview, the conceptual work done by two political scientists in the area of paradiplomacy will be discussed. The eight agreements will then be compared and analyzed. The article will conclude with a summary of how these Memoranda of Understanding shed light on the theoretical work.