This article is concerned with the links that exist between control of inter-organisational relationships and effects of proximity. We propose a theoretical framework which explains how geographical and organisational proximities reinforce formal and informal control mechanisms. This framework is then used to analyse mechanisms of control by proximity in a French aerospace cluster. We observe that formal and informal control is concentrated in a small number of groups located near the majority of the establishments members of the cluster. We also show that informal control mechanisms require a stronger geographical proximity than formal control mechanisms in order to operate.