Ambulance control involves distributed group work using a mix of computer and communications technologies. The implementation of computer technologies has had mixed results in this area, evidenced by serious failures in the London Ambulance Service in 1992. Often failures are due to inadequate attention to integration of organizational and technical aspects of work. We report a field study of the organization of one aspect of the work of ambulance control, locating the scene of an emergency. The study was carried out in two ambulance control centres, one predominantly urban and highly computerized and the other largely rural and minimally computerized. Our analysis shows that the particulars of `locating the scene' are best seen in terms of the use of different technologies to link representations and represented. This research has implications for understanding task and context and the integration of technology and organization in design, particularly with respect to using similar computer-based technologies in both ambulance control centres.