This project is currently undertaking a comparative study of the formation and maintenance of Virtual Organizations (VOs) in two leading collaborative science networks: the Long Term Ecological Research Network (LTER) and the Open Science Grid (OSG). Both LTER and OSG are mature enterprises for supporting multidisciplinary scientific research; however, they differ in the nature of their VO tool use. LTER uses a broad variety of tools to sustain organizational communication at a distance (e.g., listservs, conference calls and face-to-face meetings), while OSG has sought to delegate key components of organizational life and maintenance to Grid-based mechanisms (e.g., authentication and authorization protocols). Using ethnographic and comparative methods, and drawing on theories from science and technology studies (STS), organization science, and human-computer interaction, we compare the different approaches taken by LTER and OSG to: i) provide a better and more sophisticated mapping of the characteristics of individuals, groups and organizations that embrace VOs; and ii) develop rigorous comparative models for the differential human and technical work which sustain VOs.