This paper tries to explain the temporal evolution of electronic commerce in a developed country. For this purpose, we evalúate the contribution of the size of the potential market represented by the community of Internet users to the development of electronic commerce, as well as of other determinant factors. The validation carried out, for the whole Spanish market and over a period of seven years, reveáis the existence of a critical threshold of online consumers that, once surpassed, supposes a change in the growth trend of electronic commerce. Likewise, we verify that broadband technology diffusion, the definition of a legal framework of consumer protection, and the design of a valué proposition perceived as "secure", also influence the development of electronic commerce. We also confirm the contribution of firms’ differentiation strategies to the development of electronic commerce, to the detriment of those based on price leadership. Finally, it seems that possession of a computer is no longer an indicator of access barriers.