Productivity gains associated with investments in information technology (IT) have generally not been forthcoming. One construct that is seen as influencing the extent of individual productivity gains associated with utilising IT is user acceptance. Studies have identified a range of factors that influence acceptance in contexts where use is voluntary. However, in many modern workplaces systems are mature and embedded, affording users limited discretion over use. The current study, therefore, identified factors that influenced acceptance of a mature and embedded computer system, and identified ‘number of applications’ and ‘perceived usefulness’ as appropriate measures of acceptance for such systems.