This thesis investigates the political and legal dimensions of human rights policies enacted by cities in order to respond to one main research question: how are these policies enacted and what is their outcome? Drawing on the human rights and urban politics literature, this research provides a first comprehensive overview of human rights discourses, laws and institutions enacted by municipalities against the background of conflicts and tensions between cities’ economic and security priorities and the many social questions and problems generated by the increasing differentiation of local populations. Within this broad and unified theoretical framework, this study looks also at the differences emerging from local human rights policies that can now be found in very different areas of the world. Private and public actors - from individual experts and NGOs to cities (and their networks) and international organizations - act as policy agents diffusing human rights among cities. While often relying on a human rights framework, in fact most of these policies implement anti-discrimination measures, focusing on formal and/or substantial discrimination in both its individual or collective dimension. In order to respond to the main research question, this thesis employs a most different case type of comparison addressing the policies and institutions of two cities - New York and Barcelona - with special attention paid to the fields of employment and housing. The human rights polices of the two cities differ in many respects but also present some similarities. In New York, the core of the policy is the City Commission on Human Rights, one of the many local anti-discrimination agencies present in US cities. The Commission implements the city’s Human Rights Law. The Commission has operated under the 'umbrella' of the US civil rights legal and political framework. In Barcelona, human rights are 'pushed' by the City Department on Civil Rights and its two bodies: the Office for Non Discrimination, which is an antidiscrimination agency modeled on the US type of civil rights agency, and the Inter-religious Center of Barcelona dealing with religious communities. Different aspects of the politics and law of human rights in the two cities are considered, from ethnic discrimination tied to migration to gay, lesbian and transgender issues. The thesis shows different approaches in the implementation of the human rights policies and different degrees of visibility and effectiveness by the city departments in advancing their human rights agenda. The comparison of the 'law enforcement' and 'law support' work of the Commission and the Office for Non Discrimination shows similarities in issues of discrimination tackled by the two bodies but also their different capacities of remedying discrimination by relying mainly on mediation: while the Commission in New York has been forced by excessive workload and eventually political pressures to shift its main focus away from litigation, the Office of Barcelona’s mediation is hindered by constraints placed upon it by state defined regimes of citizenship, the systemic and complex nature of discrimination and the lack of adequate investigative and remedial powers. Issues of group-related rights of religious minorities emerge in both cities, with the Center of Barcelona operating with the ambiguous perspective of both supporting these rights and controlling religious minorities for security purposes.