The research enterprise increasingly involves multidisciplinary collaboration, sometimes over geographic distance. Technological advances have made these collaborations possible, and the history of past innovations suggests these collaborations are desirable. Yet multidisciplinary projects can carry high coordination costs. This study investigated how collaborations address disciplinary differences and geographic dispersion to coordinate people and tasks to achieve success. We conducted an inductive study of 62 scientific collaborations supported by a program of the U.S. National Science Foundation in 1998 and 1999. Projects with principal investigators in more disciplines did not appear to suffer more coordination losses and reported as many positive outcomes as did projects involving fewer disciplines. By contrast, geographic dispersion, rather than multidisciplinarity, was most problematic. Dispersed projects, with principal investigators from more universities, were significantly less well coordinated and reported fewer positive outcomes than collocated projects. Coordination mechanisms that brought researchers together physically somewhat reduced the negative impact of dispersion. We discuss several implications for theory, practice, and policy.