The object of this grounded theory study was an information system development (ISD) project. The project included two private sector organizations. The data were collected by 15 in-depth interviews. Glaserian grounded theory method was used as the technique for theory building. The main contribution of this study is a substantive theory of ‘Paradoxical views of strategic ISD and change management’, presented in the form of propositions. Theory includes the analysis of managerial and organizational contradictions when aiming at coping with changes and decreasing uncertainties during the ISD project. The theory explains also how the trust-based collaboration formed during the years enabled an excessive optimism among the decision makers. The pre-existing ISD structure did not fully support the actions required for the strategic Information System (IS) change which polarized the decision making and management. We argue that the findings of this study have some valuable implications to researchers who aim to understand the emerging issues and tensions in the development of a business critical IS product.