The analysis of the main determinants of intra-firm diffusion of digital technologies is becoming in the focus of attention. However, there is a lack of empirical research, particularly in Europe. This paper proposes a specific approach to modelling intra-firm diffusion process by combining the well-established models of technological diffusion with organizational and networking complementarities view and epidemic evolutionary approaches. Our investigation is based upon a survey conducted in 2003 for 2038 enterprises by the Catalan government. Three econometric models are then tested. The first one is an ordered probit model where we test the probability of ICT adoption by firms. Secondly, we built a general model explaining intra-firm diffusion of ICT according to some specific tools as well as to different business uses of these digital technologies. Our results confirm the well-established literature. Thus, the main conclusion of this paper is that inter-firms ICT diffusion (i.e. investment in digital equipment) and ICT depth of adoption (i.e. spread of efficient digital uses), have different determinants, although they share some common traits based on the existence of complementary effects between digital technologies, innovation, organizational structure and workers skills within a firm.
