In the knowledge‐based economy, organizational success is dependent on how effectively organizational employees share information. Many studies have investigated how different types of communication activities and communications media influence knowledge sharing. We contribute to this literature by examining increasingly prevalent yet understudied IT‐mediated social interactions and their effects on knowledge sharing among employees in comparison to face‐to‐face social connections. By integrating the literature on knowledge sharing, social networks, and information systems, we theorize the ability of IT‐mediated social interaction to (1) afford interactions between individuals with heterogeneous backgrounds and (2) facilitate frequent IT‐mediated social interactions that are high in competence‐based trust—both supporting effective sharing of knowledge. Through a social network analysis of the employees in a high‐tech organization, this study finds that IT‐mediated frequent social interactions are the most effective in promoting knowledge sharing.