Introduction: An emerging research area within the social sciences is infrastructure studies. This article conceptualises school libraries as an infrastructure among others, allowing for a fresh look at the role of the school library. We review and discuss what constitutes the school library as an important infrastructure at a school site. Method: Empirical data drawn from a qualitative interview study, including qualitative observations of Swedish school libraries was analysed using the concept of infrastructure. Analysis: The analysis was conducted with the support of a model including structures and arrangements of infrastructures. Results: A central objective of school library practices is to make the library more visible as one of the infrastructures of a school site. Different aspects of school library infrastructure can work for and against visibility. Conclusions: By conceptualising school libraries as an important infrastructure among others at school sites, it was possible to develop a deeper understanding of school library practices and visibility. Findings from this study contribute to the research on school libraries as contested functions within the context of schools.