This paper reports on our research into the relationship between spatialpatterns and ideology in two 'Informal' towns in southern Africa. Using theanalytical techniques of space syntax together with the social theory ofstructuratlon an attempt Is made to show how urban space 'works' as boththe medium and outcome of power relations in society. Social patterns ofdomination and resistance are spatially constituted in urban designs, and byhighlighting this soclo-spatial interplay key lessons are provided for ar-chitects on the sub-continent.In their attempt to overcome the anti-social and sterile effects of modernarchitecture and urban design in southern Africa architects have directedtheir attention at the more informal, or organic-looking, settlement in theregion. These range across a wide spectrum of settlement types, from theiraditional' towns in Botswana and the older segments of cities such as CapeTown that have evolved piecemeal during the last 150 years, to squattersettlements around the larger industrial centres.A morphological feature underlying all these settlements Is that they areseemingly without design, or order. Their complex, distorted geometry sug-gests an unintelligible environment without structure and without any formof planning logic. In plan, therefore, 'informal' settlements present S a finemosaic of narrow streets, winding walkways and Irregular shaped squaresand meeting places. Vet, on closer inspection, what at first appears to be disorderly and confus-ing turns out to be an immensely sophisticated spatial system. This is so be-cause the design of this settlement type at the global level has been deter-mined mostly as the result of numerous decisions taken at the local level.Since these decisions are, in effect, the spatialisation of social ideas, includ-Wing those tacitly taken-for-granted conventions that give structure to theway people Interact and ultimately how society is ordered, they are not al-ways explicit In the appearance of settlements. Indeed it is not that these settlements are without planning but that the rulesof composition governing their design are different. Each settlement is thus,in effect, a complex web of interlocking spatial decisions informed by a setof locally generated rules. In order to identify those rules, or 'the designlogic', research has had to go beyond the level of appearances and style andinvestigate the pattern of spatial relationships that is defined by the builtforms that make up the settlement as a whole.This paper presents this research in order to demonstrate that any attemptby architects on the sub-continent to design better environments with onlya superficial understanding of form will most likely lead to a spurious solu-tion, essentially no different to the ones being criticised. It adopts the tech-nique of 'space syntax' (Hillier and Hanson 1984) which is used in combi-nation with the social theory of 'structuratlon' (Giddens 1984) and appliesthis model to two case studies: Crossroads, a 'squatter' settlement near CapeTown; and Serowe, a 'traditional' Tswana town.In each instance the ideological framework which forms the non-physicalcontext of design is unique and both the set of design rules and the spatialmorphology vary accordingly as two distinct spatial cultures. Crossroads Isbasically an enclave of conservative, Xhosa-speaking people who since themid-1970's have constantly been threatened with removal by the State. Po-litical tensions both within the community and between the community andthe State have frequently erupted into violence, culminating in a major con-frontation in 1984/5 and the destruction of a large portion of the settle-ment. Major aspects of these power relations are spatially constituted in theform of the settlement.Serowe is typical in form of the informally produced settlements in Botswa-na. It consists of numerous households organised into clusters, or wards,each of which is under the control of a wardsman, and all wardsmen are re-sponsible to a chief.. This hierarchical pattern of relations is clearly arti-culn both case studies the relationship of social organisation and spatial de-sign Is demonstrated to be non-trivial and deeply embedded in form. It isargued, In conclusion, that urban design and architecture are forms of ma-terial Ideology crucial to the reproduction (and transformation) of societyon the sub-continent.