This paper investigates the importance of proximity (both relational and geographical) for partnership formation in innovation systems, in which there is an assumed tacit aspect to knowledge flows. Once presented our rationale for an agent-based modelling approach to understand these phenomena, we describe the model where we define two types of agents: firms and institutions. The former aim at innovating and therefore are involved in a continuous learning process which occur both individually and interactively. The latter, on the other hand, play a supportive role, facilitating knowledge flows among firms which possess complementary skills.