This thesis analyzes the Public Library System of the State of São Paulo, from 1984Paulo, from to 1996 the light of cultural policy theories. In order to do so, historical information was collected, official documents were presented, libraries were mapped in order to prospectively discuss the public library in society. In addition, the selected bibliography was read in relation to cultural policy, public library and cultural action, in order to support the discussions held. The thesis is divided into two writing blocks, respectively, "Cultural Policies and Public Libraries" and "The Public Library System of the State of São Paulo". During the research, we found that the Public Library System of the State of São Paulo was anchored in the commitment to the Democratic State, with the stimulus to the participation of society in the activities carried out. Likewise, we can infer that one of the greatest legacies of this entire historical process -the creation of the Library System -, in the time frame studied from the documentation used, was the use of cultural action in its activities. This initiative sought to promote transformation in the lives of people and communities, through public libraries in the municipalities.