Does a professional newslist enable its subscribers to build up knowledge and, if so, of what kind and through what processes? To answer these questions we analyse two corpuses of messages from the abds-info list, one consisting of questions and the other of syntheses of answers. Based on interviews with subscribers, we then try to identify their treatment of these messages. Our findings show the key role, in interaction, of practical knowledge which is strongly contextualized and related to a goal. They also reveal many treatments, of varying levels, which seem to allow the extension of knowledge to partially controlled fields better than the creation of knowledge in new fields. In her conclusion the author examines the situation of learning consisting in participation on a list and its possible use in contexts of distance learning.