This study examined 2 leader functions likely to be instrumental in synchronizing large systems of teams (i.e., multiteam systems [MTSs]). Leader strategizing and coordinating were manipulated through training, and effects on functional leadership, interteam coordination, and MTS performance were examined. Three hundred eighty-four undergraduate students participated in a laboratory simulation modeling a 3-team MTS performing an F-22 battle simulation task (N = 64 MTSs). Results indicate that both leader training manipulations improved functional leadership and interteam coordination and that functional leader behavior was positively related to MTS-level performance. Functional leadership mediated the effects of both types of training on interteam coordination, and interteam coordination fully mediated the effect of MTS leadership on MTS performance. (Contains 12 tables, 1 figure and 5 footnotes.)