The World Bank remains one of the most prominent actors in the field of global development, and one of the foremost international organisations in contemporary global politics. Over its history, its lending for housing has developed by prioritising financial sector expansion over the needs of low-income groups. Through this book, Liam Clegg explores the factors influencing change in the World Bank's operational practices, and the contribution of these operations to state transformations across the global South. The author outlines three main operational phases, in which the Bank prioritised: improving informal settlements, strengthening governments' housing finance programs, and expanding mortgage markets. Constrained experimentalism is identified as the driver of this changing focus, with trial and error-based learning interacting with personnel shifts and borrowers' reform trajectories to shape outcomes. In addition to reviewing relevant institutional dynamics at the World Bank, particular attention is paid to the impact of projects on housing system transformations in Mexico, China, and Tanzania. Overall, the declining focus on the housing needs of lower-income populations leads Clegg to label World Bank lending in this area as an exercise in mortgaging development. This valuable study of the field will be an important resource for researchers, postgraduate and advanced undergraduate students from across the fields of political science and international studies.