Having established itself, town and country planning, like any other field o f policy, needed theory: to provide it with values, aims and methods; to give it professional integrity; to present itself to the world; and to organize professional training. There is a distinction to be made between theories for and theories of planning. The former were those used in planning while the latter show how it operates in society, and as often as not these are what are meant by the term ‘planning theory’ . This is one thing that makes it difficult to come to grips with theory in planning. Another, paradoxically, is its own poverty o f ideas. As a practical discipline, it was not too concerned with theoretical issues but tended to stick to the ideas formed during its evolution, or to borrow from other fields. Its practitioners justified this by the intrinsic and lasting value o f the dictates o f Howard and other founders; but i f no equivalent ideas were put forward for twentieth-century patterns, in particular for all that developed around economic growth and then the ‘end’ o f growth, the risk was obvious.