— Advanced communication technologies enable strangers to work together on the same tasks or projects in virtual environments. Understanding the formation of taskoriented groups is an important first step to study the dynamics of team collaboration. In this paper, we investigated group combat activities in Sony’s EverQuest II game to identify the role of player and group attributes on group formation. We found that group formation is highly influenced by players’ common interests on challenging tasks. Players with less combat experience are more likely to participate in group events for difficult tasks and team performance is positively correlated to group size. Keywords- activity focus theory, bipartite network, group formation, massively multiplayer online game