History suggests that a large and secure middle class is a solid foundation on which to build and sustain an effective, democratic state. Can we hope, then, that the recent rise of new, large middle classes in some developing countries will be good for governance in those countries? How dependent are new middle classes on continuing growth? Who is “middle class” in the developing world? And under what conditions does a large-enough middle class have a benign effect on a country’s politics and policies? Finally: Should governments in the rich world, and institutions like the World Bank, aim to build and nurture the new middle classes, and if so how?