This report provides a new perspective to the nature of urban sprawl and its causes and environmental, social and economic consequences. This perspective, which is based on the multi-dimensionality of urban sprawl, sets the foundations for the construction of new indicators to measure the various facets of urban sprawl. The report uses new datasets to compute these indicators for more than 1100 urban areas in 29 OECD countries over the period 1990-2014. It then relies on cross-city, country-level and cross-country analyses of these indicators to provide insights into the current situation and evolution of urban sprawl in OECD cities. In addition, the report offers a critical assessment of the causes and consequences of urban sprawl and discusses policy options to steer urban development to more environmentally sustainable forms.