There is a growing sense that the North American low‐density and automobile‐dependent urban form is unsustainable from the perspectives of quality of life, economics and the environment. Yet for all the calls for a transformation of development patterns, trends inherited from the post‐second world war period die hard. This article employs structuration theory to generate a conceptual framework that identifies factors of structural stability and transformation. It then uses this framework to account for difficulties in achieving a transition to higher density and less automobile‐dependent forms of development. The evidence originates from Toronto and points to an uncertain transition in urban development. The article closes with a consideration of society‐wide implications of the difficulties in redirecting structural tendencies when an environmental crisis looms on the horizon.