Introduction This is a proposal for a PhD study. The study attempts to look into how residential choice behaviour expresses the preference of the residents of Dar es Salaam city and how the choices affect the urban form and quality of the city. In the study the theory/concepts of lifestyle will be used to understand their choices while typo-morphology will be used as a tool to analyse the quality of the different residential areas chosen and will be basis of the presentation. GIS will be used to analyse and display the spatial information. The research methodology will include both quantitative and qualitative methods. The expected results will be a better understanding of how lifestyle affects residential choices particularly in a Third World context.Why did you choose to live in this area? Where did you live before coming here? What are the qualities that attracted you to live in this area? These are some of the questions whose answers ultimately influence the choices that people make on where to live. Rapoport (1985) says that people choose in order to increase congruence between needs, wants, and their environment, between lifestyle and their environment. Changing lifestyles for instance in developed countries was an influential factor in sub-urbanization. Similarly low-income people in developing countries attach great importance to kinship and social ties when choosing a place to live (Ozo, 1991, Lindert 1991). Research ProblemThe proliferation of informal settlements in Tanzania continues unabated resulting in high densities in core areas of the city and haphazard land development in the peripheral and hazardous areas. The key question is what factors influence people’s choice of residence and in particular those choosing to live in informal settlements and how these are expressed in space. The relationship between urban planning and design and; human spatial behaviour needs to be explored in order to understand how our choices affect the urban form and quality and vice versa. Research ObjectivesThe main objective of the study therefore is to investigate the factors people find important in selecting where to live and how their decisions spatially influence the form/structure of the city. Specific Objectives of the research are:1. To investigate the factors underlying choice of residential area of households in Dar es Salaam City.2. To ‘map’ the spatial dimension and characteristics of the different residential locations and compare them to the preferences.Theoretical FrameworkThis study intends to use the concept/theory of lifestyle as a determinant for residential choice. Rapoport (1985) argues that lifestyle……. and residential choice can be matched. This is because a person’s lifestyle is related to education, income, class, ethnicity, stage in lifecycle, which influences residential choice. Aero (2000) citing Murie (1974) points that through housing and residential choice, lifestyle preferences attempt to be realised. Informal residential areas in Dar es Salaam are not homogeneous and while they maybe lacking in basic services, they do not all manifest poor environmental and socio-economic characteristics like other squatter settlements in developing countries probably because of differing lifestyles of their inhabitants. In order to relate the choices to urban form and spatial quality the preferred residential areas will be analysed using typo-morphological urban analysis which provides an appropriate framework to study the areas in detail. It is possible to evaluate the relative attractiveness of different urban types using typomorphological urban analysis (Radberg, 1998).MethodologyBoth qualitative and quantitative methods will be used in the study. A socio-economic survey using questioners and interviews will be done in two informal areas of Dar es Salaam city. One area will be that of low-income and the other a middle/high income area in order to get a comparison of preferences. Informal areas are chosen because almost 80% of residents in Dar es Salaam are accommodated in them, the areas lack basic services like water, roads and drainage but the houses built are of good quality. I may decide to choose areas close to the centre of the city and those on the periphery. Both owners and renters will be interviewed. Analysis will be done using a statistical package and GIS for the spatial information.