In the introductory part of this paper we give different definitions of public relations activities and a brief overview of the ways this activity is performed in Serbian libraries. In Serbia, only the National Library of Serbia has a special department for public relations; none of the libraries have engaged a professional agency for these tasks, and only a few of them have planned, in their job systematization, position of one or (rarely) more than one person who should, in addition to their other duties, deal with public relations. In the main part of the paper we present the organizational model and methodology in the field of public relations of the Belgrade City Library, in order to enable interested colleagues - in libraries that still do not have any or have a poorly developed PR strategy - to obtain guidelines for its development. The work does not consider all the relationships that this public library establishes with the target groups, but focuses on two of them which are, according to the author, the most important ones: the media and the active and potential library users. In the Belgrade City Library the Cultural Programs Department is in charge of public relations, therefore the paper describes mainly the activities of this department. Although public relations in the Belgrade City Library is rather developed, there is a need for its further improvement. The key measures that should be implemented in this regard are as follows: development of a long-term PR plan, analyzing appearances of the Library in the media, intensification of work in promoting the municipal libraries and branches, intensification of relations with politicians and sponsors, improvement of internal communication - informing all the employees about the current activities and long-term plans of the Library, organization of training in the field of internal and external communication. [ABSTRACT FROM AUTHOR]