The paper proposes that the concept of responsibility provides a means of identifying and specifying, in a way that is meaningful both to users and systems designers, the organisational requirements that arise when a technical system is placed in a social context. The paper shows how organisational structure may be represented as a network of responsibility relationships, how requirements arise from the discharge of obligations associated with responsibilities, and how these concepts have been applied to the particular example of specifying user requirements for clinical workstations in acute hospitals.