Despite many numbers of studies in Technology Acceptance Model(TAM), the social influence construct has not been recognized, nor handled clearly. This study includes the social influence construct in TAM and tests the robustness of the model for different information systems contexts: office automation(spreadsheet) and Internet(WWW) usage. Study findings include that 1) social influence has a direct impact on the usage of spreadsheet, but not on Internet(WWW) usage, and 2) social influence has a stronger indirect impact on IS use through perceived ease of use than through perceived usefulness(for both Internet and spreadsheet).