During enterprise system implementation, organizations transfer system-related knowledge to end users through training sessions and by having them involved in the system design and implementation processes. However, during actual use of the system, end users acquire informal knowledge from co-workers through their social networks. Existing research has focused on the structural features of social networks and their impact on regulating knowledge flow between end users and across the network. The personal attributes and preferences of end users that could impact their knowledge acquisition and processing capabilities have not been considered. This paper examines the expertise level of end users, their gender, and the complexity of their job tasks in influencing system-related knowledge acquisition and its impact on performance outcomes. Data for this study was collected from active users of a new Enterprise Resource Planning (ERP) system that had been implemented across multiple business units of diversified business conglomerate in the United States.