This paper is based on case study research conducted with thirty-four Australian SMEs. It develops a framework for identifying and analysing the factors influencing SMEs ability to derive benefit from conducting web-based EC. Adapting the work of Venkatraman (1994) the paper begins by presenting a model of E-business transformation exploring the relationship between the degree of SME organisational transformation and the potential benefits to be derived from EC. This four phase model is used as a basis for examining the range of internal and external factors that influence SMEs ability to engage in these types of organisational transformations and to derive benefits from EC. The factors are grouped into two categorises: internal and external. From analysis it emerges that depending on their nature, these factors generate inhibiting or enabling forces on an SME’s ability to engage in EC business transformation. More specifically, within any particular phase it is the interaction between these inhibiting/enabling forces that directly influence the ability of an SME to derive benefit from the conduct of web-based EC. Significantly the case study analysis also indicates that where SMEs have already engaged in a high level of EC business transformation (phase 4 Enterprises) their ability to derive further marginal benefit from EC becomes increasingly linked to the nature of factors external to the enterprise.