The basic model that long run GDP growth can be approximated by the ratio of export growth to the income elasticity of demand for imports is remarkably robust. Neverthgeless, the connection between trade parameters, foreign growth, foreign interest rates and trade ratios in the determination of a sustainable accumulation of foreign debt requires economists to organize analysis in terms of trade parameters, foreign conditions and a sustainable debt-income ratio to understand the impact of global imbalances in the world economy.