The funding measure „Internationalization of leading-edge clusters”, which IfW researchers have accompanied scientifically, promotes international openness and international exchange of leading-edge clusters. Its aim is to combine advantages of spatial proximity with those of international R&D-cooperation. The authors show that the share of international activities that have been conducted as part of the cluster-internationalization has risen considerably. Research institutions are the main drivers when it comes to establishing international contacts and implementing R&D-projects. When it comes to innovation and international activities, young firms benefit more from cluster ties than older firms. Particularly in biotechnology and medical technology, regional ties within the cluster are especially important for initiating international activities. Innovative clusters can play a vital role in overcoming future technological challenges, especially in case of broad international linkages.