In response to a call for new content and instructional techniques in the teaching of mathematics, the Public Broadcasting Service (PBS) has launched an organization called MATHLINE, whose first project involved facilitating electronic communication among mathematics teachers nationwide. This document describes a study which examined the members' reasons for joining such a group (MATHLINE in particular), the types of communication fostered, and the perceived benefits of involvement. Messages were downloaded and sorted into statements, questions, and replies. Statements were further scrutinized for elements of fact, opinion, and parable. Questions were subdivided into the pragmatic and the programmatic. Results indicated that replies, whether answers or supporting evidence or yet more questions, were the most frequent kind of teacher-to-teacher online communication. It is hoped that analysis of these messages might be carried further into research on the roles played by different members of an online learning community and the communication patterns between them. Many sample messages are included verbatim. (Contains 13 references.) (BEW)