The purpose of this paper is to illustrate how librarians and teachers work together and with the help of other research try to understand what influences this cooperation. The study is based on the following questions: 1. These two professional groups have different professional identities and work in two different professional cultures. How does this affect their cooperation? 2. Which of the two professional groups decide what reading promotion work is to be done? 3. What do these two occupations think of their own and each other’s skills and how does it affect the cooperation concerning reading promotion? The chosen method is interviews with two librarians and two teachers who are all involved in reading promotion. Two theories were used as a theoretical framework: Lena Folkesson's three professional dimensions and Louise Limberg and Lena Folkesson's three categories of perceptions regarding cooperation. The results are largely in line with previous research and an important conclusion is that the cooperation is improved if librarians and teachers work towards a common goal regarding reading promotion in schools. Such a goal should clarify the roles and responsibilities for each participant. This clarification is an important step towards a school library which is well integrated into the school, and it will give librarians real legitimacy in order to take on an active role in the cooperation. These factors reduce the tensions that can arise when two different professional cultures meet, and also prevent a situation where the two professional groups are trapped in traditional roles.