‘‘Post-normal science’’ (PNS) has received much attention in recent years, but like many iconic concepts, it has attracted differing conceptualizations, applications, and implications, ranging from being a ‘‘cure-all’’ for democratic deficit to the key to achieving more sustainable futures. This editorial article introduces a Special Issue that takes stock of research on PNS and critically explores how such research may develop. Through reviewing the history and evolution of PNS, the authors seek to clarify the extant definitions, conceptualizations, and uses of PNS. The authors identify five broad areas of research on, or using, PNS which have developed over four decades. Their analysis suggests that the 1990s represent a symbolic watershed in the use of PNS terminology, when the concept was further developed and applied to highly complicated issues such as climate change. The authors particularly distinguish between uses of PNS as a normative prescription and as a practical method. Through this classification, they set out gaps and research questions arising. They then briefly summarize the Special Issue articles and consider their relationship to each other and the research questions raised by their analysis. They conclude by considering what the articles in this issue suggest for future theory building in PNS and related scholarship.