: Most cooperation support systems require information about the organisational context in which they are used. This is particularly required when systems are used in a large organisation or for the support of inter-organisational cooperation. Following from this requirement, this paper presents the design and functionality of the organisational information system TOSCA for cooperation support systems. TOSCA is composed of two major components: an organisational information base server, which provides services to applications and an organisational information browser, which provides user access. The paper describes the motivation for an organisational information system, the object oriented data model that is used for the information representation, the architecture of the overall system, and the design of the user interface that presents and provides access to the multimedia information. It concludes with the description of how this system supports a task management system and the rol...