What does it mean to be a central participant? An actor can participate in a single episode of an activity, and she can also participate within a community. The degree of participation can be greater or lesser depending on a number of factors. The primary participants are those that make direct contributions to an episode of activity. The secondary ones witness the action but do not make direct contributions. To be a central participant within a community depends on the number, kind, and ways in which the individual participates in the set of activities performed by the community. It also depends on the participants knowledge of events and episodes that occur within the community, whether the actor directly participated or not. The study that is presented provides an analysis of the semesterlong work of students in a co-blogging community.