This paper explores the arguments for and against a common currency for Canada and the United States and attempts to determine whether such an arrangement would offer any significant advantages for Canada compared with the present flexible exchange rate system. The paper first reviews the theoretical arguments advanced in the economics literature in support of fixed and flexible currency arrangements. A discussion of Canada's past experience with the two exchange rate systems follows, after which there is a survey of the empirical evidence published on Canada's current and prospective suitability for some form of fixed currency arrangement with the United States. The final section of the paper examines critically a number of concerns raised about the behaviour of the current flexible exchange rate system.