Abstract: | “Why projects are late” is a fundamental issue in theory and in practice. One well‐established explanation is that a project's network structure can be a significant factor—the “fatter” or more parallel the project, the later the project completion. Herein we show that a lack of agility, which may frequently arise in projects when there are external resources, can also be a significant factor in project delays—both in more serial‐like projects as well as more parallel ones. Specifically, this article formally characterizes the concept of agility in projects, shows how a lack of agility can have a significant impact on a project, and gives some general properties on agility with respect to a project's structure. |