In March 1989, Treasury Secretary Brady unveiled a new U.S. initiative to deal with the debt problems of the lesser developed countries (ldc's), which by then had beset the world's financial communities for 8 yr. The plan encourages the commercial banks and the debtor countries to negotiate a debt restructuring with an eye toward reducing the debt burden of the debtor countries. It would require the banks to forgive a portion of their loans; in return, the world bank and the international monetary fund would guarantee their remaining ldc portfolios. The idea is that debt reductions would allow the debtor countries to retain more resources for economic development, thus facilitating their ability to grow out of their debts and defusing the crisis in the end. Many of the highly indebted ldc's that could benefit from the Brady plan are resource- rich, major mineral producers. As their economies improve, some of the macroeconomic factors that affect their mineral production costs could also change. Concerned about how such changes could affect the international competitiveness of U.S. mineral producers, the U.S. Bureau of Mines conducted this study, covering copper in Chile and Mexico. Chile and Mexico were selected because the former is the world's top copper-producing country and the latter is the major ldc for which debt reduction has been successfully negotiated and implemented under the Brady plan.