This paper deals with an intriguing paradox that can be observed in today’s regional economic policy making: whereas unique local factors are increasingly seen as the determinants of regional economic success, simultaneously more and more governments try to copy policy experiences that proved to be successful in a particular region. A good example here is the use of ‘best practices’ in the field of regional cluster policy. Cluster programs are becoming like ‘mantras’ for policy makers who want to stimulate regional economic development. Given this paradox, in the present paper we address the question what lessons can be drawn from comparing success stories of regional clustering. To answer this question, we combine insights from regional economics and comparative public policy. To start, we discuss the literature that has led to the popularity of the cluster concept as a learning device among policy makers. After that, we identify the preconditions (‘contingencies’) that affect whether these cluster policy initiatives can be transferred from one place to another. We find that some of the contingent influences, especially those related to the degree of uniqueness of an area’s economic structure and culture, hamper the possibility of ‘learning by comparing’ in regional cluster policy. It may even be argued that exactly those regional specificities explain the success of cluster–based policy efforts. Thus, we have to draw the rather pessimistic conclusion that the possibilities of lesson–drawing in regional cluster policy are limited. In our view, at best ‘best practices’ should be seen as inspiration sources rather than as recipes for successful regional economic development.