Many governments have established cluster policies to foster innovation and support hightech industries through agglomeration economies. They attempt to boost networks through providing clusters with resources to organise heterogeneous support activities. A key question is which support activities are the most important for firms. In this study, we investigate the German biotechnology industry based on a survey of dedicated German biotechnology firms (n = 92). We find that i) members of biotechnology clusters primarily take part in events related to network development and fundraising, ii) they do so by a much greater extent than firms outside of clusters. We then show that firms in clusters are more likely to engage in R&D collaborations, to attract public R&D grants or private investments, and to be innovators.