The purpose of this article is to examine the communication behaviors of online leaders, or those who influence other members of online communities in triggering message replies, sparking conversation, and diffusing language. It relies on 632,622 messages from 33,450 participants across 16 discussion groups from Google Groups that took place over a 2-year period. It utilizes automated text analysis, social network analysis, and hierarchical linear modeling to uncover the language and social behavior of online leaders. The findings show that online leaders influence others through high communication activity, credibility, network centrality, and the use of affective, assertive, and linguistic diversity in their online messages.