In the Swedish library law, there is a clause that indicates that every municipality shall have a ‘library plan’. At the time of 2015, approximately a third of the municipalities in Sweden did not. The aim of this thesis is to map out the most important prerequisites for the development of library plans, and what the top managers of the public libraries see as important for the process. The material used for the study consists of interviews with the top managers of public libraries from municipalities with library plans and data collected from all municipalities in Sweden about the resources libraries have. The results of the study shows that municipalities without a library plan spend fewer resources on the public libraries and they have fewer librarians. Lack of time and staff are important problems for the development of library plans, but also insufficient collaboration between different parts of the municipal organization. The most important prerequisites for the development of library plan are interested politicians, enough time and resources allocated, and that the different parts of the municipal organization want to cooperate.