The ‘polycentric urban region’ (PUR) has become a key concept in regional studies, both as an analytical framework to capture empirical realities as well as part of normative visions and goals in regional development policies. In its most basic guise, the PUR notion applies to regions characterised by the presence of multiple, more-or-less proximate urban centres without pronounced hierarchical differentiation between those centres. Given the alleged increased conceptual, empirical and policy relevance of PURs, the Regional Studies Association (RSA) has decided to (co-)fund a research network dedicated to enhancing our understanding of the prevalence, significance, and future development of PURs. To officially launch of this research network, its coordinators will be organizing paper sessions at the 2018 RSA conference in Lugano. The purpose of these sessions is to develop a timely overview of the present state of PUR knowledge in the broadest possible sense, which will in turn inform the key themes that will be tackled in the remainder of the research network’s activities.