The author describes the history of Canadian-American environmental relations, emphasizing the institutional structures and legal principles that were put in place to facilitate management of these relations.He points out that a collegial or joint approach to data production is essential if these systems are to work effectively and deplores the current manner in which the acid rain controversy is being handled.By manipulating science rather than allowing the scientists of both nations to work together freely within the acid rain joint Canadian-American work group structure set up for this purpose, the present administration is not only refusing to face the reality of acid rain but is causing great damage to the institutions and principles that have governed Canadian-American environmental relations for the greater part of this century.