This paper examines the potential role of energy efficiency and economic efficiency in influencing the future carbon dioxide emissions of developing countries. it explores and offers support to the hypothesis that, despite the potential value to the developing world of greater energy efficiency, if tight restrictions on global carbon dioxide emissions were considered necessary, efficiency alone could make only a limited contribution to restraining the projected growth of developing country emissions. This is because of the projected rapid energy growth rates in most developing countries, especially in the industrial sector and from fossil-fuelled Electricity and transport, associated with growth in per capita incomes and population. The potential contribution of other possible measures to address global carbon dioxide emissions, particularly fuel-switching, is also briefly examined.