Urban form is changing in Britain, with new patterns of development reflecting economic, technological, and transportation conditions in an increasingly competitive framework. Changes in urban form have implications for the environmental sustainability, integration and cohesion, and longer term quality of life in and around cities. Britain has a comprehensive planning system with a strong rhetoric of policies towards these goals. In this paper the authors draw on evidence from recent research, primarily in central Scotland, to assess how far planning actually does make a difference to urban form rather than simply passively responding to demand. They consider some of the systematic tendencies in decentralised planning decisionmaking, some selected evidence of development outcomes, and some insights from major development case studies. The conclusions highlight the differential influence of planning between different development sectors and the obstacles to achieving a more sustainable pattern.