Global virtual teams (GVTs) can provide benefits in terms of lower costs and enhanced performance. However, the realization of these benefits depends on effective GVT task coordination, which faces significant challenges due to time-zone differences and geographical dispersion. Further, there is a lack of understanding of optimal information-technology (IT)-mediated coordination mechanisms for these teams. Based on an in-depth study of project tasks carried out by three GVTs, we uncovered IT-mediated task coordination portfolios (sets of mechanisms) used for effective coordination. The portfolios should fit the GVT's task dependence, members' common time frame, and perceived time constraints in order to be effective.