Background Neighbourhoods have been the focus of attention of city planners, architects, and urban designers for a long time. It is a powerful idea and has occupied a well-entrenched place in the minds both of theoreticians and of practitioners for many years. Yet a close analysis of its meaning reveals an extremely elusive concept whose substantive charac- teristics ebb and flow over time. The meanings attached to the idea are continually being disassembled, shuffled, and reassembled according to the circumstances. Neighbourhoods are often seen as solutions to urban social problems, stemming from the deterioration of local community ties, which are assumed to have been based in preindustrial cities on frequent face-to-face encounters. (1) As a proposed cure for these urban deficiencies, the neighbourhood introduces clear physical definitions, organized local institutions, and a communal pattern of activities. (2) Thus, despite its diverse theoretical meanings, (3) the neighbourhood often serves as a basic building What is a neighbourhood? The structure and function of an idea Rachel Kallus, Hubert Law-Yone Faculty of Architecture and Town Planning,Technion, Israel Institute of Technology, Haifa 32000, Israel; e-mail: arkalus@techunix.technion.ac.il; hubert@techunix.technion.ac.il Received 10 June 1999; in revised form 18 February 2000 Environment and Planning B: Planning and Design 2000, volume 27, pages 815 ^ 826 Abstract. In this paper we use the tension between ideals and reality as a key to comprehend the ever- changing concept of neighbourhood in architecture and planning theory. We analyze the theoretical, that is abstract, meaning of the concept of neighbourhood by using a deconstructive approach in the examination of particular texts. A shift in the sense and meaning of neighbourhood in architecture and planning theory over the years is discerned. A stratified process of transformation in the meaning attached to the neighbourhood is identified in the arguments used to construct this idea in theory and in professional practice. This process proceeds from a humanistic approach, to an instrumental and then to a phenomenological approach. The humanistic approach sees the neighbourhood as a manifestation of human activity and thus the planning of the neighbourhood as a moral requirement which is a proper response to basic human needs. The instrumental approach views the neighbourhood as a plan- ning device, an integral building block in the development of urban structure. As such it conceives of the neighbourhood as a subsystem in a larger assemblage. The phenomenological approach empha- sizes the neighbourhood as a unique urban phenomenon. Its significance is seen to stem from its conventional everyday function (residential) which involves continuity and permanence and which fixes the neighbourhood sense of place in the urban collective memory. In our paper these three approaches are related to present architectural and planning attempts to come to terms with both overall general societal developments as well as with specific demands and needs situated in the profession. (1) These views are based on antiurban sociological approaches, as apparent, for example, in the writings of Durkheim (1972), Park et al (1925), Tonnies (1955), and Wirth (1938). Other urban theorists, such as Simmel (Wolff,1950), for example, in his 1903 essay ``The metropolis and mental life'' (Wolff, 1950, pages 409^424) see the industrial city as an opportunity for a reevaluation of traditional values. For a discussion, see Tafuri and Dal-Co (1976). For a discussion of the impact of sociological theory on urban planning, see Saunders (1981). It should be noted, however, that the thrust of the present paper is towards the meanings attached to the idea and less with sociological studies of the object. (2) The literature on neighbourhoods is most extensive and diverse. However, most writers agree that the neighbourhood is a definable, imageable, and manageable residential area (Brower, 1996). (3) For further discussion of the various meanings of the neighbourhood and its use, see Kallus (1991) and Kallus and Law-Yone (1997). DOI:10.1068/b2636