World Bank researchers have been trying to assess the extent of extreme poverty in the world since 1979. Two ingredients have been key: an international absolute poverty line and purchasing power parity (PPP) exchange rates. The latest PPP update led to a substantial re-assessment of relative purchasing powers around the world, and hence to a large nominal change in the poverty line: from $1.25 to $1.90/day. Join us for this month’s Policy Research Talk as Francisco Ferreira reviews the principles, practices, and pitfalls involved in the latest update, and then discusses some of the ideas being floated for the future of global poverty measurement.