Periodically, spatial planning gains an important position on the agenda of those concerned with the management of economic and social change. This tends to be the case in economies of the developed as well as the developing world. Attention is initially given to the nature of spatial planning and to some of the reasons why it might represent a justifiable involvement, both at the level of the nation and the region, where the implications of ignoring these concerns have sometimes been very serious. There is a further set of occasions, however, when spatial planning may be dangerous. Under these circumstances it is common for objectives to be phrased in spatial terms, and for non-spatial (e.g. sectoral or functional) concerns to be subordinated to spatial ones, in such a way that spatial planning assumes an unwarranted dominance in the overall planning process. The consequences of spatial factors exerting such a dominance are no less serious than the consequences of their being neglected. The discussion concludes with an examination of some of the more general difficulties that confront spatial planning.