In recent years, there has been a rapid growth and widespread adoption of social media technologies across all industries. Despite the growing importance of enterprise social networks (ESN) in creating social capital and facilitating innovation, there has been limited research in examining the role of employee relationships (ties) in these networks. Earlier studies have reported that the network structure can enhance or restrict employee behaviour to a great extent and that those who implement ESN should consider how network structure can support positive collaboration behaviour, rather than restrict it. Accordingly, we propose that the understanding of network ties and their effect on employees’ collaboration will help in influencing the design and use of ESN in a way that it will help in building productive and sustainable employee collaboration. This paper reviews the existing literature to understand the relationship between network ties and collaboration outcomes and proposes a future research agenda.