Traditionally, economic geographers stress geographical proximity's positive impact on collaboration processes. However, effects of cognitive, organizational, social and institutional proximity dimensions have been emphasized recently. This paper examines the relations between geography and these non-spatial dimensions by distinguishing two mechanisms: the substitution mechanism, where non-spatial forms of proximity substitute for geographical proximity; and the overlap mechanism, where geographical proximity facilitates non-spatial proximity. The two mechanisms’ importance is analysed in collaborative innovation projects in the Danish cleantech industry. Regression models are complemented by a qualitative analysis of the relationship between the geographical and institutional dimensions.