Since the 1990s there has been a rapid growth of science parks, often established to function as engines of (regional) economic growth. Knowledge exchange between on-park firms in general, and between these firms and universities in particular, is one of the key characteristics of a science park. This paper regards knowledge exchange as a type of network behaviour. The paper answers three research questions: What are the knowledge exchange behaviours of on-park firms? Can we distinguish different types of behaviour among these firms? If so, what are differences between these groups? To answer these questions, we take a relational approach in which actor and relationship features are studied in a sample of firms located at the Innovation Hub (South Africa). Preliminary results show that there are two groups of firms: on-park firms that network with other on-park firms and those that do not. Moreover, there are interesting differences between these groups: On-park networkers have in comparison more informal ties with off-park firms than the other group (non-on-park networkers); they are able to gain more useful knowledge from private knowledge sources; and they have more access to unintended knowledge that flows in the park. Despite different knowledge exchange behaviours, the innovative performance of the groups does not differ.