The thesis focuses on purchasing strategies at Swedish public libraries. By applying professional theory, gatekeeping theory, and the theory of tacit knowledge, the study highlights the challenges and power dynamics that influence the selection of literature purchases in library collections. My research problem consists of a hypothesis where public librarians are seen as gatekeepers, which can have a direct or indirect impact on the purchases made, presenting a democratic dilemma. Previous research has shown that there is a lack of clear guidelines on how purchases should be handled, and where the library law can be interpreted differently. The purpose of my thesis is to examine the perspectives of librarians and see if there are variations between different libraries regarding purchasing strategies, as well as highlight what might underlie these differences. My source material includes interviews, media plans/media policies, library plans, and I conduct a qualitative case study. From the results of the study, I conclude that certain differences exist between various public libraries, and this depends on whether decisions are made individually by a purchasing manager or by a purchasing group, as well as factors such as experience, time constraints, and budget that influence purchasing strategies. The impact and differences based on the political governance in the municipality where the public libraries are located proved to be relatively small. I argue that there is some evidence to view librarians as gatekeepers and that this affects the collections in Swedish public libraries.