This case study discusses variation and formalization strategies for managing technology-use mediation of Web-based groupware technologies in an organizational context. Research and development projects of a multi-national pharmaceutical company entail a close collaboration between many geographically distributed actors. The use of a groupware technology in long term, cross-disciplinary and distributed development projects has been investigated in order to understand how Web-based technologies for collaboration become part of organizational work practices. In this paper, the work of project assistants in setting up and promoting the technology is described and analyzed as technology-use mediation. The ways in which the project assistants position themselves as system administrators by delegating access rights, providing content, and advocating use among development project members are identified as crucial to the integration of the groupware technology in work practices. Two configurations of the groupware technology and the cooperation within the development projects are compared under the metaphors of “the ultimate communication tool” and “a set of private and safe workspaces” respectively. The differences between them are brought forth to discuss the roles of the project assistants and the variety of ongoing meta-structuring activities. In conclusion, formalizing the technology-use mediations is discussed as beneficial if it renders the position of the project assistants more visible within the organization. This need not induce uniformity of configurations across the development projects, but might strengthen the mediating position of the project assistant and how well the groupware technology is suited to the local work practices.