 Public action and sustainable districts: cognitive and organizational issues 
Sustainable development (SD), which is based on three main pillars, environmental, economic and social, to which the cultural has been added, has become a main reference of urban public policies. As a result of Agenda 21 of the 1992 Rio Summit, cities adopted local SD programs of action. The design and implementation of these programs raise cognitive and organizational issues. This is the case of the City of Montreal, which first puts forward, under the responsibility of a sectoral service, a program favoring the development of sustainable neighborhoods with an interpretation of the SD focusing on environment, before launching a new program, integrating other dimensions of SD and going hand in hand with an administrative reorganization.