This work consists on a study about the practices of the Social Workers at the Leão XIII Foundation, within the shanty-town of Vila Ipiranga, located in the city of Niterói, Rio de Janeiro. The goal of this study is to describe the limits and possibilities for a social assistance institution, from the point of view of its professionals and clients. Furthermore, this study intent to highlight the perspective of the Social Workers, who are historically linked to state-control institutions and, as a consequence, operates under the institutional concept of material and moral assistance to the poor. In our society the place of residence constitutes criteria for social discrimination, in accordance to a ranking of urban spaces. Within this ranking, since the beginning, the slums are perceived as an urban space that disqualifies their residents and, therefore, they constitute what we call stigmatized territories. The identity of the shanty-towns residents is constructed, for themselves and for others, as a social stigma, which is experienced on their day-to-day social, professional and institutional relations, including the state-controlled institutions related to health care, education, security and social assistance. This work wishes to learn from the Social Workers, and from the clients of the social assistance institutions, the contribution of the Leão XIII Foundation to the process of construction, maintenance and up-dating of the social stigma imposed to the residents of the shanty-town of Vila Ipiranga who are clients of the programs and services offered by the Foundation.