This paper addresses the evolution of the network structure of a virtual organization over time. Data has been collected on the E-mail messages exchanged by the members of a virtual organization at two points in time, 4 years apart. Social network analysis will be used to compute, and compare across time, two measures of emergent network structure – degree of hierarchy and centralization. Structure will be assessed both at the level of the overall organization as well as for each of principal 3 task categories – design (the core task of the organization), group maintenance, and resource management.