In this paper the author identifies a widening gulf between theory and practice in planning during the last decade, in Britain at least. The reasons for, and implications of, this gulf are discussed. The author begins by attempting to 'identify' planning and to clarify the meanings of 'theory' and 'prescription'. It is argued that both theory and practice are undermined by their separation and that it is essential for the development of planning that the two come back together. The theory-practice link needs to become a major focus of attention both for academics and for practitioners.