The paper deals with a process known in economic theory as the internationalization of industrial clusters. According to the author, clusters are subject to internationalization at two levels: the micro level, or the level of firms taking part in clusters; and the meso level, or the cluster as a whole—through the work of organizations responsible for coordinating the cluster’s operations. Industrial clusters have entered a new stage of development in their role as projects designed to stimulate competition, Jankowska notes. They no longer limit themselves to local, regional or national markets, but are increasingly eyeing international markets in their operations. This enables them to combine the benefits of clustering with the effects of internationalization, the author says. Jankowska uses a deductive approach to investigate the cluster internationalization process. Her research methods include an in-depth, critical literature review focused on the concepts, models and indicators of the internationalization of a firm and reports on the internationalization of cluster initiatives. Another research method is based on in-depth interviews with managers and coordinators of selected clusters in Poland. On the basis of the research, the author highlights the mechanism of internationalization of clusters and shows the degree of internationalization in some Polish clusters. The main conclusion is that Polish clusters are still only marginally involved in the process of value creation in international markets, according to Jankowska. Internal structural problems caused by the attitudes and policies of managers are a principal barrier that prevents Polish clusters from taking full advantage of the benefits of internationalization, Jankowska concludes.