This paper introduces a micro-founded methodological framework to estimate the housing deficit across and within emerging economies. It introduces the Adequate Housing Index, which provides a comparable assessment of adequate housing based on seven adequacy dimensions that are held constant across all countries. The adequacy dimensions were obtained and harmonized from countries’ most recent household expenditure and consumption surveys. The paper documents large differences in housing adequacy across a sample of 64 emerging economies, as well as wide within-country disparities such as across income groups, locations, and occupations. Estimates of the Adequate Housing Index show that across the sample of 64 emerging economies, there is a current housing deficit of 268 million housing units affecting 1.26 billion people. About 26 percent of the current housing stock in these economies is inadequate. The paper further estimates that at least 40 million additional housing units will have to be added by 2030 to provide adequate housing to all and accommodate the growing population and urbanization patterns.