Computer Supported Cooperative Work 12: 205–219, 2003. © 2003 Kluwer Academic Publishers. Printed in the Netherlands. 205 Intermediary Objects as a Means to Foster Co-operation in Engineering Design JEAN-FRANÇOIS BOUJUT & ERIC BLANCO Laboratoire 3S, BP 53, 38 041 Grenoble cedex 9, France (E-mail: Jean-francois.boujut@inpg.fr) Abstract. In this paper we argue that co-operation is a particular way to co-ordinate an industrial activity and that it is particularly suited to collaborative design activity. Through a well documented case study of the development of a front truck axle, we point out several key features of co-operation in an industrial setting. We particularly pay attention to the interfaces between the actors involved in the collaborative process. We observed the pre-eminence of the representations and the objects created, manipulated, and finally we claim that they support knowledge creation and therefore allow the development of a common understanding of the design situation (i.e. the problem and the solution). We propose the concept of “intermediary object” as a conceptual framework for the involvement of objects in the design process. We demonstrate the power of this concept in the analysis and modelling of particular design situations and in the development of specific objects that foster co-operation in real design situations. Key words: collaborative design, computer aided design, concurrent engineering, empirical studies, intermediary objects 1. Introduction Today the concept of concurrent engineering is being implemented in an increas- ingly high number of companies. The design process 1 is very deeply impacted by these evolutions and this invites researchers to propose new models, methods and tools. Our research effort is directed towards the understanding of co-operation in design and the development of devices that foster it. Although we think co- operation is a natural way for reaching a goal collectively, it is all but natural in an industrial setting. More precisely this way of co-ordinating is mixed with the traditional modes of co-ordination consisting of planning and task decomposition in an informal way, leading to underestimating the importance of co-operation. However, we often observed that performing joint work on the same product led to the development of specific types of interactions, specific knowledge, skills and attitudes. Particularly we want to highlight here the importance of the material involved in co-operative processes. More specifically we will study the role of different types of objects as mediators in the building of shared representations. It is important here to differentiate between the roles of an object as representation, knowledge support, convention and even participant of the design process as rightly stated in Perry and Sanderson (1998).