Networks of Practice (NoPs) facilitate knowledge sharing among geographically dispersed organization members. This research tests whether social influence in NoPs is reinforced by actors' embeddedness in practice (knowledge about informal content), organizational embeddedness (knowledge about formal organizational content), structural embeddedness (knowledge about who knows what), and relational embeddedness (knowledge about informal relationships). A full-fledged automated content analysis on all postings on four NoPs maintained by a multinational chemical company revealed four dimensions in communication content that largely coincide with the proposed embeddedness types. We measured social influence by assessing to what extent actors' use of uncommon language traits was adopted in the responses to the postings. Hypothesis testing revealed that network members who communicate about informal practice, and know who knows what, exert more social influence than others. The results suggest that network members' social influence is rooted in their utilitarian value for others, and not in their organizational or relational embeddedness. © The Author(s) 2011.