Task dependencies drive the need to coordinate work activities. We describe a technique for using automatically generated archival data to compute coordination requirements, i.e., who must coordinate with whom to get the work done. Analysis of data from a large software development project revealed that coordination requirements were highly volatile, and frequently extended beyond team boundaries. Congruence between coordination requirements and coordination activities shortened development time. Developers, particularly the most productive ones, changed their use of electronic communication media over time, achieving higher congruence. We discuss practical implications of our technique for the design of collaborative and awareness tools. Categories and Subject Descriptors H.5.3 [Information Interfaces and Presentation]: Groups and Organization Interfaces – collaborative computing, computersupported