This paper is an account of the World Bank's effort to collect household-level data on poverty in developing countries and what that data says about the effects of government policies on living conditions of the poor. The main objective of the Living Standards Measurement Study (LSMS) surveys is to provide household-level data for evaluating the population's living conditions. This paper gives a history of LSMS and shows general trends that emerged in studies for which LSMS data are available: (a) most of the poor are in rural areas; (b) most of the poor are in households in which the head works in agriculture; and (c) the heads of poor households have low levels of education. Selected results of studies on the persistence of poverty, the effects on the poor, structural adjustment, food stamps and food subsidies, and raising user fees for health care and education are presented.