This article underlines the main implications of the interrelations between the energy problem and that of environmental pollution, using the most widely used macroeconomic indicators in the field of policy analysis. In fact, carbon dioxide (CO2) emission intensity and energy intensity trends may be used to highlight the most important features of economic development over a given time scale in a variety of different countries. The empirical analysis proposed here-covering a time-span of some 40 years in a number of the most highly industrialised nations-seems to be useful if we are to understand the main similarities and differences in the interaction between the energy choices made by different countries and their respective environmental effects. Moreover, by using PPPs, it has been possible to propose a more detailed cross-country analysis for the different international situations.