In this paper we propose a simulation model aimed at describing the emergence and the dynamics of innovation networks, with particular emphasis on the role of open knowledge disclosure. It is argued that firms that widely disclose knowledge to other firms are more likely to enter innovation networks and to acquire a central position within these networks. By disclosing knowledge, firms increase their reputation, which indicates to other organizations that they are competent, and that it is worth starting a partnership with them. The higher a firm reputation, the higher its probability of entering new R&D partnerships with other firms. Our model provides, therefore, a rationale for behaviors of open knowledge disclosure by showing that such strategies, although risky in the short run, may pay in the long run by enabling firms to access external sources of knowledge more easily.