he purpose of this bachelor’s thesis has been to gain a further understanding of children’s librarians development of and view of their competence and the way it is shown during their work with book clubs for children. The study is based on the following questions: how do children’s librarians define their competence during their work with book clubs for children? Which mediation roles do they express during their work with book clubs for children? How do they develop their competence during their work with book clubs for children? Semi-structured interviews with four children’s librarians were conducted. The analysis was carried out within a thematic framework based on Jofrid Karner Smidt’s (1994) mediation roles and Etienne Wenger’s (1998) theory of communities of practice. The key findings are that children’s librarians define their competence by describing words such as creativity, flexibility and empathy. The ability to build relationships and a true interest in children and children’s literature is also defined as key competences in their work. The result also shows that children’s librarians do express each one of Karner Smidts five mediation roles. The last finding in this study is that they develop these competences and skills mainly by joining the community of practice which is constituted by children’s librarians profession. Our ambition with this study has been to contribute to the research that distinguishes children’s librarians competence, an area which we believe is in need of further investigation.