Post-Normal Science as a theory links epistemology and governance. It not only focuses on problem situations where facts are uncertain, values in dispute, stakes high and decisions urgent, but also tries to develop epistemic approaches that allow for sound scientific answers. The following article addresses major epistemological challenges within a typical ‘‘wicked-problem situation’’, i.e., risk assessment of emerging technologies. Such challenges include epistemological problems intrinsic to the task of proving the absence of risk, problems related to the multi-sited production of (...) evidence and the multitude of epistemic cultures involved, the incompatibility of the various implicit objectives and the complex actor-constellations, that shape not only the way scientific knowledge is translated into action, but also which kind of knowledge is produced and which experts are listened to. To illustrate and discuss these characteristics, the article draws on an empirical study of risk research in the fields of agri-biotechnology and telecommunication technology in Germany. It concludes that although some aspects of PNS are already part of current epistemic practices in these fields, a state of ‘‘functional post-normality’’ depends upon a meaningful co-evolution between post-normal science and post-normal governance that has not yet been achieved. (shrink)