The objective of this paper is to review previous research on convergence of carbon dioxide emissions among countries. We discuss the key findings in this work, how the choices of model, data, statistical tests, etc. influence the results, and highlight some policy implications. The empirical research on convergence in per capita carbon dioxide emissions shows some evidence of convergence between developed (OECD) countries, while at the global level there appear to be relatively persistent gaps or divergence. These results are however sensitive to the choice of econometric approach and data set (e.g., the length of the time series). Still, the empirical basis for an egalitarian rule of equal per capita emissions in the design of global climate policy is not solid; it ignores the specific structural characteristics of countries such as climate, natural resource endowments, etc. The analysis therefore points to a need for more in-depth analyses of the structural determinants of carbon intensity (productivity) at the country level, as well as to additional research on the economic consequences of different types of equity principles (including combinations of such principles).