This study describes the development and testing of a new instrument to measure user satisfaction. We have called this the System Satisfaction Schedule (SSS), and the associated statistic, S. In essence, this instrument is based on user-generated complaints. The findings suggest that the SSS is a viable instrument for measuring user satisfaction, despite the lack of positive factors assessed. Other factor-based instruments may be unreliable, since they can omit factors that are important to the user, or include factors which are of no significance to the user. The SSS avoids this difficulty by rating factors which are almost entirely user-generated.