Despite significant progress in recent years, the evolution of commons over the long run remains an under-explored area within commons studies. During the last years an international team of historians have worked under the umbrella of the Common Rules Project in order to design and test a new methodology aimed at advancing our knowledge on the dynamics of institutions for collective action – in particular commons. This project aims to contribute to the current debate on commons on three different fronts. Theoretically, it explicitly draws our attention to issues of change and adaptation in the commons – contrasting with more static analyses. Empirically, it highlights the value of historical records as a rich source of information for longitudinal analysis of the functioning of commons. Methodologically, it develops a systematic way of analyzing and comparing commons’ regulations across regions and time, setting a number of variables that have been defined on the basis of the “most common denominators” in commons regulation across countries and time periods. In this paper we introduce the project, describe our sources and methodology, and present the preliminary results of our analysis.