The main theoretical objective of this research is to establish the structuring role of the socio-spatial dimension in the organization and distribution of services to marginalized populations. Empirically, this involved taking an inventory of housing resources for five types of clientele within the Montreal Urban Community: psychiatric patients, the mentally deficient, ex-prisoners, the homeless, and drug addicts. By sector of inventory, the analysis of the data confirmed the presence of a process of ghettoization of marginalized populations. Globally, 5.5% of the sectors inventoried account for 45.5% of the 6,451 beds in the territory analyzed.