Addis Ababa’s housing sector has been a long-standing challenge. For over a century the rapidly growing Ethiopian capital has been unable to provide adequate and sufficient housing, particularly for its low-income citizens. By the early 2000s, Addis Ababa’s 4 million inhabitants stood against an accumulated housing backlog of 233’000 units. Against this backdrop, the Ethiopian government collaborated with the German Technical Cooperation (GTZ) to address the housing issue through a city-wide mass housing program. This paper follows the program’s successive stages of implementation during the 2000s and addresses the social as well as spatial results along two of its main conceptual pillars: individual home-ownership through a mortgage system, and highly standardized housing block typologies. Whereas the program has created amounts of housing units unseen in Ethiopian history, it has also revealed substantial challenges on spatial and socio-economic levels: the program has failed to provide wide-spread affordable housing to the targeted low-income groups; it has generated spatial and social segregation; it has fostered dependency on imported materials; it lacks design features and spaces that reflect local lifestyles and daily needs; and it has accelerated the peripheral expansion of the city. In summary, the paper argues that the two described conceptual pillars of mortgage finance and standardized housing blocks have been key catalysts for the described challenges. Based on this, it seems obvious that effective low-cost housing concepts for Addis Ababa – whether as alterations or as new approaches – would have to specifically engage with design processes and funding schemes from more flexible, versatile and inclusive vantage points.