Information systems institutionalisation is a process through which technology becomes aligned with the organizational environment and, thus, becomes an integral part of the organization. Technology implementation in contemporary business organizations should not be viewed as one off endorsement of technology. Instead it is an important ingredient in the ongoing process of organizational evolution through which the business maintains its legitimacy, power, and social and economic fitness. For successful information systems institutionalisation, organizations need to consider technical, organizational, social, environmental, cultural, political, and other institutional aspects. It is important to emphasize these factors because they not only shape technology, but also help in its assimilation and routinization within the organizational context. This paper establishes that an organization as an institution consists of various sub-institutions, where the mutual complementary interaction of these sub-institutions gives legitimacy and social and economic power to the organization. It presents a framework for information systems institutionalisation which explores the character, shaping, and use of technology through continuous interfacing with technical, contextual, social, cultural, environmental, and other sub-institutions. This research particularly highlights the critical success factors for institutionalisation of information systems at each stage from their assimilation to deinstitutionalisation and reinstitutionalisation.