The abstract from the website of the JID:
Two decades ago, most of the world's poor lived in countries officially classified as low income. Now, most of the world's poor live in middle-income countries. The shift has been brought about by fast growth in a number of countries with large populations. This ‘new geography of global poverty’—with the mass of the poor not living in the world's poorest countries—raises questions for the current model of development assistance, where national per capita income is a key determinant of the volume and composition of aid flows. This paper reprises the changes in global poverty and discusses the case for continued development assistance to middle-income countries.An early draft is here (February 2011).