Requirements determination (RD) during information systems delivery (ISD) is a complex organizational endeavor, involving political, sensemaking, and communicative processes. This research draws on the analytic concept of technology frames of reference to develop a socio-cognitive process model of how frames and shifts in frame salience influence sensemaking during requirements determination. The model provides a theoretical and conceptual perspective that deepens our understanding of requirements processes in organizations and of the socio-cognitive basis of power in ISD. The paper reports on a longitudinal case study, in which four technology frame domains were identified and the influence of frames on project participants' understanding of requirements was traced through eight RD episodes. Repeated shifts in the salience of the business value of IT and IT delivery strategies frames disrupted project participants' understanding of requirements and contributed to a turbulent RD process. Analysis of frames and framing helped explain how interpretive power was exercised, yet constrained, in this project. Implications for further research and for practice are considered.