Notwithstanding the proliferation of studies linking e-commerce with the macro-environment, theoretical frameworks on the institution-e-commerce linkage are not well developed. Our primary purpose in this paper is to extend theory on the institution-e-commerce linkage by explicating the influences of normative and cognitive institutions on individuals’ and firms’ e-commerce adoption behaviors. Broadly speaking, the approach employed in this paper can be described as a positivistic epistemology. The paper takes a conceptual or a theory-building approach. We first develop a conceptual framework that represents how a technology’s interaction with normative and cognitive institutions affects a firm’s relationships with the profession, other businesses and customers. We then apply the framework to develop a set of propositions on normative and cognitive influences on a firm’s e-commerce adoption behaviour. Our analysis indicates that normative and cognitive institutions, in spite of being less visible than regulatory institutions, are no less important in shaping the diffusion pattern of e-commerce.