Dr. Iftekhar Ahmed's forthcoming article titled "Stability of Membership and Persistence in Teams: Impacts on Performance" in the journal Group Dynamics: Theory, Research, and Practice investigates the impact of membership stability on performance in action teams which engage in multiple tasks over time using a sample of 4871 teams from a Massive Multiplayer Online Game. The study contrasts closed teams in which membership is constant over time with open teams in which membership changes over time. Results suggest that closed teams were more successful than open teams. The number of times a team played had a quadratic relationship with performance for closed teams and a linear relationship with performance for open teams. Results also suggested that variability in membership had positive effects in that open teams were able to sustain their effectiveness for a longer time than closed teams. The study, co-authored with Dr. Marshall Scott Poole of the University of Illinois Urbana-Champaign and Dr. Andrew Pilny of the University of Kentucky, was supported by the National Science Foundation (NSF), the Army Research Institute, and Air Force Research Lab.