The Pediatric Pain Mailing List (PPML) is an international Internet-based forum for informal discussion of any topic related to pain in children. There are now over seven hundred members, including clinicians, researchers and patients from at least forty countries on six continents. Currently, the archive contains more than ten thousand messages. The goal of this research is to provide a means by which the tacit knowledge captured in the archive can be organized and accessed in a fruitful manner. This involves the threading together of e-mails such that the threads represent asynchronous discussions and question-answer sessions and then clustering these threads hierarchically such that the PPML archives can be browsed easily.