This working paper, produced by the Mitigation Action Plans and Scenarios (MAPS) programme, investigates the relationship between emissions, inequality and poverty in middle-income countries in Africa and Latin America. Research on this topic is of particular importance, since changing global demographics mean that the majority of the world's poor now live in middle-income countries.The paper finds that, with economic growth contributing to greater emissions, a trade-off appears between the two that decreases as a country’s gross domestic product (GDP) grows. Further analysis suggests that environmental degradation increases and then declines as GDP grows, but carbon emissions continue to grow with GDP. The relationship between inequality and emissions is also discussed; evidence suggests that in relatively equal societies, increased inequality correlates with decreased emissions, with the inverse suggested for countries of high inequality, i.e. lower inequality/lower emissions (shown on a graph as a shallow 'U'). The research suggests that there is an opportunity for the growing number of middle-income countries to both reduce emissions and combat poverty. However, only the most unequal poor countries could do likewise, because most would suffer a significant trade-off between the two.Two case studies, South Africa and Brazil, are analysed to investigate the relationship between per capita emissions and inequality in middle-income countries. In Brazil, rates of emissions and inequality reflect the development and economic choices of successive governments. Until 1994, emission and inequality levels closely correlated, rising and falling together. Since then, GDP and emissions have grown, but redistributive social policies have seen inequality decrease. In South Africa, a long history of inequality founded on racial segregation has contributed to lack of reduction in inequality alongside economic growth, with per capita emissions remaining steady. With emissions largely concentrated in the coal-based energy sector, South Africa is well placed to design mitigation actions while continuing social policies aimed at poverty reduction and reducing inequality.