THE empty acres of Londons docklands will puzzle future generations of historians. How, in one of the most densely populated countries in the world, could so much space lie waste for so long? How could an area on the edge of land with some of the highest values in the world fail to attract private interest? How in a country with one of the most sophisticated planning systems in the world could residents and employers complain of cramped and inadequate buildings, and yet redevelopment continue to disrupt areas of activity while neglecting the areas of wasteland? Since 1974, in the process of researching the planning and development of London's docklands, I have been able to compare the progress in different places. I have followed closely the fate of the grand schemes. I have also had a first-hand insight into the process of urban decay and regeneration through my involvement in setting up a number of projects in the Outstanding Conservation Area of St Mary's, Rotherhithe. The result of this work has been to discover that we have attacked the wrong 'bogeymen' for the failure of our cities to live up to our expectations. Property developers and planners could be blamed with some justification so long as there was the pressure of demand to ensure competition for what land should be used for. This was the product of a rising population and an expanding economy. But with a static or falling population, and a declining manufacturing base to our economy, a very different situation results, and one for which neither local authorities nor private companies are prepared. The experience of the London docklands is therefore not just an interesting case study but a possible model of how great cities can decay when they lose the ability to adapt to change in an evolutionary and incremental way. This can best be understood by first reviewing the reasons why the docks became vacant, then contrasting the experience with schemes involving redevelopment and conservation, before proposing a new explanation of the process of urban change, which focuses on the interaction of systems rather than on the role of individual actors.