This Master’s thesis describes two case studies of mobile delivery robots operating in hospitals by moving equipment and goods between depart- ments where human employees work. Through contextual interviews with employees who operate and maintain the robots, and observations in the robots’ environment, I describe how work is distributed between humans and robots, and how the design of robots may affect how well they work. I have seen that a large number of errors occur and because of this, robot operators and other colleagues must do additional work for the robots to do their part of the work. I distinguish between facilitation and articulation work to describe the additional tasks that humans do. I use pre-, peri- and post-facilitation to describe additional tasks related to adapting the robots’ physical environment. I argue that peri-facilitation is the least convenient, and can be reduced by increasing pre- and post-facilitation. Articulation work is divided between the work of planning how the tasks are going to be carried out (first order) and additional work that is done when unexpected contingencies arise (second order). I suggest that the inconvenient, unexpected articulation work can be reduced by focusing on the planning. The perspective on robots as part of the cooperative ensemble reveals that the causes of errors are mostly related to them not being designed con- sidering the dynamic, unstructured environment in which they operate. I present two design implications to reduce the amount of additional work required when using mobile robots; design to enhance operator’s aware- ness of the robots’ context and to adapt the robots’ interaction to their con- text of use.