Deforestation is a phenomenon that has largely been concentrated in the developing world. We construct a theoretical model of deforestation that focuses on the factors affecting the incentives to transform forested land into agricultural land. We show that: (i) lower discount rates and stronger institutions decrease deforestation; (ii) a depreciation in the real exchange rate increases deforestation in developing countries whereas the opposite obtains in developed countries; (iii) paradoxically, better institutions may exacerbate the deleterious impact of a depreciation in developing countries. These hypotheses are tested on an annual sample of 101 countries over the 1961-1988 period, and are not rejected by the data. Our results suggest that short-term macroeconomic policy, institutional factors, and the interaction between the two, are potentially important determinants of environmental outcomes.