Mutual learning and infrastructuring are two core concepts in Participatory Design (PD), but the relation between them has yet to be explored. In this article, we foreground learning in infrastructuring processes aimed at change in the public sector. Star and Ruhleder’s (1996) framework for first, second, and third level issues is applied as a fruitful way to stage and analyze learning in such processes. The argument is developed through the insights that arose from a 4-year-long infrastructuring process about future library practices. Framed as Co-Labs this process was organized by researchers and officers from the local regional office. This led to adjusted roles for both PD researchers and civil servants working with materials at the operational and strategic levels. The case shows how learning led to profound changes in the regional public sector in the form of less bureaucratic and more participatory experimental and learning-focused worldviews and practices.