This study explores how school librarians in Swedish primary schools develop their reading promotion competencies, focusing on their personal experiences with informal workplace learning. It identifies the challenges, knowledge, and enabling conditions that influence these processes and characterizes the competencies involved. The study holds theoretical significance within the field of library and information science and practical relevance for the school librarian profession. A professional theoretical framework is used to analyze documents in the form of handbooks written by school librarians about their own work. The study addresses the following research questions: What competencies are essential for reading promotion? How do librarians describe their learning and development processes regarding these competencies? What challenges and opportunities do they encounter in these learning processes? 

The results suggest that key competencies include social and pedagogical skills in literature mediation, digital literacy with language development tools, and abilities in project management and relationship-building. Librarians emphasize their pedagogical expertise and describe how they foster critical reading among students. They enhance their competencies primarily by taking on new tasks and collaborating with school staff and students. Resources that support learning include cognitive abilities and teamwork skills. Challenges in developing reading promotion competencies include a lack of support from school leadership and suboptimal collaboration with teachers. The librarians aim to influence both educational institutions and society to better recognize and value their profession. The handbooks can be seen as part of the librarians’ own agenda to promote their role within Swedish schools and society.