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This paper aims at analysing, both theoretically and empirically, the various patterns of coordination among firms and their impact on the patterns of localization of activities. For this purpose, an analytical framework is built in the first part of the paper, based on concepts elaborated within the proximity school in economic geography which emphasizes the multiplicity of spaces of reference of economic actors. Then, relations among firms are characterized using the competence-based approach in industrial organization. Based on these two analytical tools, the paper reviews the main arguments developed in the literature to explain the spatial dimension of inter-firm relations.The second part of the paper presents the results of an empirical study of firms involved in research and development activities, and discusses these results with respect to the theoretical arguments discussed in the first part. Through the study of research and development activities, which are generally viewed as both global and sensitive to local conditions as all innovation processes, the paper sheds new light on the role of space in inter-firm relations. This empirical work is especially valuable in that it allows to go further than the usual local case-studies that form the bulk of the literature. It allows to identify a number of strong regularities that, in turn, prove helpful in terms of local economic diagnosis.