As online communities become more important in young people's lives, it is important to consider who the active users are in these digital environments. Previous research has looked at the way leaders emerge in adult communities, but scholarship on young people's participation patterns has been less robust. This paper looks at the phenomenon of “super-users” or the leaders and vocal participants, in a specific online community populated by eleven and twelve year olds (tweens) and run out of an after-school program at two urban middle-school libraries. We ask why these particular young people participate more than their peers and identify these users' characteristics. We also look at the relationships between these characteristics and the young people's use of the site. Answers to these questions help us understand why some tweens' participate more than others and could help facilitate how to better engage all users.