This report compares urbanisation trends in OECD countries on the basis of a newly defined OECD methodology which enables cross-country comparison of the socio-econimic and environmental performance of metropolitan areas in OECD countries. The methodology is presented and results from its application to 27 OECD countries are discussed together with policy implication both on national growth and governance of cities. The report also includes three original papers that present the urbanisation dynamics and prospects in China and South Africa and the governance challenges resulting from the new policy agenda on cities in the United Kingdom.