Next to their traditional role as places for information provision and knowledge transmission, public libraries increasingly also function as important social infrastructures contributing to the everyday life in cities. As such, they can help to address systemic challenges such as social fragmentation, loneliness, exclusion and precarity. However, the library not merely is a social infrastructure, but becomes one each operating day through continuous labour by a network of stakeholders. This paper specifically examines library staff and their routinised practices to provide, perform and maintain the library as social infrastructure. The empirical research was carried out in four public libraries in the Netherlands and focussed on staff members who were in a 1-year post-graduate programme to become a community librarian, and their close colleagues. It consisted of two phases: first librarians were shadowed at work, followed by a focus group interview on the multiple problems librarians encounter to (re)make their library into social infrastructures. These include coping with limited space, collaborating with other institutions, difficulties to reach out to the community, financial struggles and differentiating interpretations of the library’s primary function.