The 21rst century will be marked by an ever increasing urban world. Projections predict this trend to be largest for developing nations in which formal housing markets are inefficient at meeting the increasing demand for urban housing. This unmet housing demand will continue to exacerbate the housing crisis and necessitate sustainable solutions. Past policies of slum clearance, modernist apartment projects, housing provision, self-help, sites and services, and in-situ upgrading have not been effective at solving the crisis. This thesis considers the central role that architectural elements plays in slum housing communities. Considering architectural elements in addition to the conventional elements of financing mechanisms and land tenure augments an understanding of what a successful housing project is. Analyzing six successful international slum housing projects for both conventional and architectural elements, this thesis highlights the importance of vernacular architecture as a determinant of a successful project. Appropriate, vernacular architecture will best serve the beneficiary community's built environment needs and lead to sustainable housing solutions. Central in this process is the inclusion of slum communities in the design process of housing projects.