Milan public library network has recently started to design its first strategic plan, which will provide a 4-year guidance for its 25 libraries. The strategic plan aims at reinforcing the role of Milan public libraries in the general strategic assets the whole city is pursuing in the future, such as ecological transition, digital transition, and the design of a 15-minutes city. In order to implement the decisions set by the strategic plan, libraries need to select, elaborate and use all the available data to take strategic decisions, as commonly done in a data-driven administration. This is why Milan public library is designing an approach to data that benefits from skills both of the library management and of data scientists.