Transitions to “low-carbon” development paths (i.e., to development paths with limited greenhouse gases emissions) are unlikely to be achievable solely via technological solutions: behavior, notably consumption patterns, will also have to evolve. However, an assumption implicit in most GHG emissions scenarios is that as income per capita converge across countries, households consumption patterns will converge as well, leading to potentially very high demand for energy, very high demand for natural resources and very high emissions. ECOPA precisely aims at examining how flexible the link between income per capita and consumption patterns is; and at drawing implications of these findings for future emissions scenarios. To do so, ECOPA maps and compares consumption patterns, and their evolution, in France, an “old” industrialized economy, and Brazil, a rapidly emerging economy. In both countries, a combination of econometric analysis of consumption data, household surveys and in-depth studies of representative goods and services is used to (i) map consumption patterns across income groups, and (ii) explore the determinants of their changes over time. Strong emphasis is put on obtaining consistent monetary and physical flows. This is necessary to analyze the energy and emissions implications of consumption patterns, but this constitutes a significant theoretical and empirical stumbling block. Finally, on the basis of the retrospective analysis, scenarios of how household consumption patterns in the two countries might evolve are built and their implications for energy and GHG emissions are computed.