When a firm makes a significant investment in an information system [IS], there will be pressure to measure user perceptions fairly quickly after the introduction of the system. Will perceptions be stable at that time? Galleta and Lederer (1989) showed that beliefs about an IS can be unstable, although they did so in an artificial environment in the context of instrument develop- ment. But how could we describe the change of user perceptions during the months following the introduction of a complex IS in a complex, functioning, real organization? This paper reports on a six month longitudinal study using four repeated measurements of user perceptions of an IS introduced throughout a comprehensive state University with approximately 14,000 students.