October 3, 2006 An effective exchange rate is a measure of the value of a country's currency vis-à-vis the currencies of its most important trading partners. The Bank of Canada has created a new Canadian-dollar effective exchange rate index (CERI) to replace the C-6 index that it currently uses. The CERI uses multilateral trade weights published by the International Monetary Fund and includes the six currencies of countries or economic zones with the largest share of Canada's international trade. As such, it better reflects the recent changes in Canada's trade profile, including the rise in the importance of China and Mexico and the relative decline in importance of Europe and Japan in Canada's international trade. The author describes the methodology and construction of the new index and reviews the advantages it offers over the C-6, particularly the use of multilateral trade weights, the inclusion of trade in services, and the use of more recent trade data.