Whereas more and more companies use Enterprise Social Networks (ESN) for internal knowledge management, there is still a lack of understanding how employees communicate their knowledge in ESN to support their colleagues. We approach this gap by analysing users’ roles and knowledge exchanging behaviours in a rich data set comprising more than two years of ESN usage. We identify three user roles, namely givers, takers, and matchers, regarding knowledge sharing and seeking behaviour and analyse their position in the organisational hierarchy. By applying means of Social Network Analysis, we contribute to a clearer picture of the significant role of givers and confirm findings of other studies that the majority of users behave as takers. Generally, our findings help to come to a more refined understanding of ESN usage and its role in knowledge practices.