Informal land use is analysed in this article from an integrated perspective including legal, social and cultural aspects. Thus informality is recognised to consist of three elements: illegality of land use, simultaneous use of land for living and for producing, and spatial concentration of kin-related households. Using this definition, informal land use in the barrios of Quito has been evaluated with respect to the modernisation, neoliberal and grassroots views of the phenomenon. Modernisation considers informal land use to be a problem because it deviates from the segregationist planning model. However, the empirical findings presented here demonstrate that the mixture of residential and production functions in the barrios is a viable -and for the present at least- the only solution for the socio-economic plight of the urban poor. Informal land use should therefore be viewed as a solution, not as a problem. The modernist model is seriously flawed, because it is based on values that are not appropriate to the socio-economic reality of the majority of the populations in the cities of the South. The grassroots perspective emphasizes the beneficial effects of informal land use in alleviating poverty. The empirical case studies analysed in this paper support this view. Informal land use is seen to be a valid means for the urban poor to solve problems of shelter, food production, income generation and social integration. Neoliberals argue that the main disadvantage of illegality is the absence of land titles that would enable the urban poor to borrow from formal sources and hence develop. It follows that property laws should be revised to facilitate llegalisation. There are several flaws in this argumentation. First, illegality in most barrios of Quito is not characterised by a lack of land titles. The barrio residents usually have titles to the land they occupy but instead they lack the necessary building or business permits to apply for formal credit. The issue in this case is thus not one of not complying with property laws but with land-use regulations. Second, arguing that the poor are dependent on formal borrowing for their development is not true. Informal networks are a successful -albeit vulnerable- alternative for the poor to finance their houses and businesses. Third, the neoliberal analysis of the disadvantages of informality has focused exclusively on economic aspects. Social and cultural disadvantages, such as the lack of sufficient and adequate public spaces in the barrios and the longterm loss of food-producing areas, are important and warrant attention. The implications of the above conclusions are that land-use policies for the barrios need to go beyond the economic and legal views. Social, cultural and ecological aspects need to be incorporated. This means that, besides reassessing land use policies for informal settlements, it is important to devise measures which support informal networks, generate public space and foster urban farming. Policy definition and implementation will only be successful when technical and financial partnerships are formed between the community, non-governmental organisations, government agencies, private enterprise and international development agencies. ; The article is available here and can be downloaded