Different educational and professional backgrounds play important roles in how school librarians prioritize activities in the school library. Whether the school librarian has a background as a teacher or as a librarian, they influence and apprehend the activities of the school library differently. The aim of this thesis is to find out how the school librarian looks at his/her commission. What shifts in priorities can be recognized depending on whether the librarian has training as a teacher or a librarian. This thesis also analyzes how the two different professional backgrounds justify their priorities in the school library. I have used Henri Tajfel’s theory of social identity as a theoretical frame work to analyze my data. My empirical data consists of four qualitative interviews and observations of award winning school librarians with different professional backgrounds; the librarians have all won the Swedish award ‘School Librarian of the Year’. The activities I observed during my field work are presented as categories in my study. I’ve used the American scholar David Loertscher’s taxonomy of school library activities to identify those categories. I then used a didactical approach to better understand the categorical data, asking the questions “What? How? And Why?” Some of my findings recognize differences between the two professional identities. A professional background in teaching tends to stress e.g. grading pupils reading abilities, whereas the trained librarian focuses more on reading for recreational purposes. My findings point out that explicit partisanship plays a major role concerning professional identity, which in the end reflects priorities in school library activities. / Uppsatsnivå: D