This paper extends the balance-of-payments-constrained (BoPC) growth model and Thirlwall's law to include the terms of trade with and without capital flows. Without capital flows a positive (negative) change in the terms of trade by improving (worsening) export performance can ceteris paribus augment (reduce) the rate of growth of an economy compatible with balance of payments’ long-run equilibrium. With the inclusion of capital flows the BoPC dynamics become more complex. Assuming no changes in the real exchange rate and in the import elasticity of demand, an improvement in the terms of trade can increase the level of the external deficit compatible with BoPC growth. This results from the terms-of-trade effects on the purchasing of exports and on foreign-capital inflows. The positive effect of an improvement in the terms of trade may be partially offset by an appreciation of the real exchange rate and an increase in the import elasticity of demand, when the model is extended to allow for such interactions in the analysis.