This article examines questions of explanation in urban geography throughconsideration of the gentrification process. Particular attention is given to the problems of 'structural' analyses and the need to develop alternative political economy perspectives.Questions related to the ways urban areas form and change are important aspects of contemporary urban geography. In recent years, concerns with the decline of the inner city, infrastructural decay and shifting social and racial balances have attracted considerable attention although it should be said that explanation of the processes at work remains a source of considerable contention. Despite this, it has become commonplace to state that we should view so-called urban processes in the context of wider social and economic forces and many analysts, whether liberal or radical, would rapidly concede the importance of the economic structure and structural change in such assessments (for example, see Hall, 1981; Johnston, 1980).A recognition of the importance of structure and the broader context is in itself uncontentious and a position many would claim to have adopted in their own work. Indeed, we have only to cast our minds back to what might be seen as the classical theories of urban structure, as exemplified by the Chicago School, to see that such work was very clearly directed towards an exploration of the impact ofeconomic development and rapid urban growth upon social groups in cities. While ecological analyses and much subsequent work, whether in the behavioural or institutional traditions, have clearly identified the distributional patterns present in urban areas, such as socio-economic groups, shopping facilities and housing, they have had much less success in developing acounts of the causal mechanisms underlying them. In that regard, recent contributions from marxist political economy perspectives have had profound impacts not only by providing cogent critiques of earlier conceptualisations but also with respect to the insights this work has offered into the nature of underlying mechanisms within the structure ofcapitalist society as a whole. In a sense this work, in its multiplicity of forms, has legitimised reference toThe Institute of Housing, 12, Upper Belgrave Street, London, SWlX 8BA.Australian Geographical Studies 22, April 1984.