ERP system deployments can result in improvements in firm performance through automation, informational, and transformational effects. Nevertheless many implementations are not successful. Employing a social network approach this study investigates the role of the IT unit in exchanging and combining knowledge focusing on the planning phase. Drawing on prior research dealing with social capital and network position this paper investigates the network position of the IT unit using the approaches of tertius gaudens (the third who enjoys) and of tertius iungens (the third who joins) to improve our understanding of why ERP implementations succeed or fail. The model is tested employing a case study in a manufacturing firm of the aerospace industry. It is shown that a tertius iungens orientation may improve the probability of successfully implementing an ERP system.