This thesis presents studies of work and discusses the relation between ethnographies of work and design of technology. Four papers based on studies from two different kinds of work settings are included. The purpose with the studies is to in detail go into some aspects of the work carried out, analyse people's actual use of technology, and contribute to the design and development of new technology. In the study of the first setting we focused on how truck drivers find their way to pick-up and delivery places. The purpose was to develop a navigation system that could support drivers finding the way when they needed. The second setting was the Swedish emergency service centres (SOS-centres). The focus here was on the handling of cases. In depth studies of how cases are handled as well as of functions in the technology have been carried out. The thesis focuses on two main questions: How do operators handle cases? What does the field studies of emergency service centre operators? work practice suggest for future design of technology? Four crucial aspects of how operators handle cases in the SOS-centres are discussed: interviewing, visibility for others, multiple calls, and parallel handling of cases. The importance of those aspects for the design and developing new technology is also discussed.