This MDP asks the question: Why has co-operative housing proven a successful and viable affordable housing option in Montréal? Through analysis this MDP recognizes that the primary conditions contributing to co-operative success in Montréal are: (1) The growing need for co-operative housing in Montréal; this is reflected physically, demographically and demographically. Physically, this need is reflected within the housing stock which displays a dramatically low vacancy rate, low ownership rates and large proportion of the population living in unaffordable housing. Demographically, this need is displayed by the citys large renter population and dependence on certain demographic groups for growth which are typically in high demand for affordable housing. These large and demographics have acquired significant political power which is reflected in the resulting public policies and programs. Economically, the citys sensitive economy reflects a need for affordable housing. (2) The programs, policies and types of support for co-operative housing in Montréal are abundant and unique within the country. Noticeably unique is the interventionist and consistent roles that the province and the Ville de Montréal have taken in terms of financing and administering programs despite political and economic changes. Privately, the development of co-operatives is significantly aided by Groupe de Ressources Techniques (GRTs) who facilitate the development process for both the co-operative and the government, resulting in more units in less time.Co-operatives work in Montréal due to a number of reasons and conditions; some which are unique to Montréal and others which are replicable elsewhere. The success of cooperatives is measured through a number of means; for Montréal, success can be displayed by the process of co-operative development within the city; the abundance and popularity of co-operative housing is just a result of this success.