Despite the important benefits for firms of commercial initiatives on the Internet, e-commerce is still an emerging distribution channel, even in developed countries. Thus more needs to be known about the mechanisms affecting its development. A large number of works have studied firms’ e-commerce adoption from technological, intraorganisational, institutional or other specific perspectives, but there is a need for adequately tested integrative frameworks. Hence this work proposes and tests a model of firms’ B2C e-commerce adoption that is founded on a holistic vision of the phenomenon. With this integrative approach, the authors analyse the joint influence of environmental, technological and organisational factors, and moreover, they evaluate this effect over time. Using various representative Spanish data sets covering the period 1996-2005, the findings demonstrate the suitability of the holistic framework. Likewise, some lessons are learned from the analysis of the key building blocks. In particular, the current work provides evidence for the debate about the effect of competitive pressure, since the findings show that competitive pressure disincentivises e-commerce adoption in the long term. The results also show that the development or enrichment of the consumers’ consumption patterns, the technological readiness of the market forces, the firm’s global scope, and its competences in innovation continuously favour e-commerce adoption.