ABSTRACTThis paper measures environmental efficiency (EE) and environmental productivity (EP) in 38 countries over the period 1971–92 and analyzes differences in these across countries. It explores several macro-economic factors that could explain these differences, such as income levels and the degree of openness in these countries. The average EE and EP indexes are found to be almost steady over the period 1971–92. In the annex-I countries, an increase in income levels initially leads to an increase in the average EE but subsequently to a decline in EE. In non-annex I countries, EE is increasing over the range of income in these countries. This study also finds an EKC type relationship between EP and per capita GDP in annex-I countries. The degree of openness has a significant positive impact on EE in annex-I countries.