This research investigates the social and socialization practices within an online professional development web seminar. The aim of this study was to identify the kinds of social and community building practices that occur in online professional development webinars by exploring how communication tools such as chat are used for community building and socializing purposes. Data was comprised of all electronically generated web seminar ("webinar"), written chat comment transcripts that were automatically generated during this series of webinars. Data were analyzed inductively and recursively using the constant comparative method. Findings revealed that the Online Web Seminars in Literacy project (oWSL) built community through moderators and participants greeting, assisting, and offering one another support. Moreover, social practices found within and across seminars included social talk, thoughtful debate, and the formation of nested affinity groups. This research revealed that this online professional development webinar provided a space where social practices like creating a sense of community through mutual support and engaging in productive disagreement among participants can stimulate informative critical dialogue that webinar organizers can draw upon to form dynamic and productive online professional development communities.