Much research on regional business clusters refers to path dependence as a central feature in the evolution of cluster structures. In many cases, however, little is known about the agentic processes and mechanisms that underlie path dependence. In this article, we explore changes in a speciﬁc network in the optics cluster in the German region of Berlin-Brandenburg to show that development of clusters can be driven by elements of both emergence and planning. In particular, we argue that current actors actively and purposively draw upon rules and resources that were shaped not only in the long and discontinuous history of the cluster but also in the recent process of network development that involves careful planning and well-structured planning tools. Using central concepts from structuration theory, we show how agency is implicated in the coordination of the network and how agency turns coordination into a self-reinforcing mechanism. The ﬁndings suggest that purposive planning involves a fundamental ambivalence in the processes and outcomes of path dependence, at the level of both the cluster and its constituent networks.