This research article provides empirical insights on the key drivers for successful internal and external innovation network management. The hypotheses are tested empirically using survey data collected from stock-listed companies in Germany, Switzerland and Austria. The data include the complete responses from 141 R&D managers for the period from 2004 to 2008. Our results show that cross-functional teamwork in R&D projects has been increasingly implemented as part of the internal network strategy. Interestingly, we found no significant effect of intensive cross-functional employee cooperation on the firms' innovation performance. According to our result, key driver for internal innovation network management is a fault-tolerant innovation culture, as it is positively related to product innovation performance. Regarding external innovation network management, the use of Web 2.0 and social networking technologies is a key driver for high product innovation performance. In addition, the results reveal the endurance of external innovation networks as a key driver for the existence of radical innovations. Innovation networks that are older than five years have a substantial positive influence on product innovation performance and on the existence of radical innovations.