Taking the informing science perspective that construes systems at three levels of abstraction, we integrated findings from prior studies into a model for system use in mandatory environments. Data collected from 333 municipal government employees using mandatory systems were used to test the model. We found that captive users' attitudes toward system use plays a pivotal role while intention to use, the central construct in the Technology Acceptance Model (TAM), loses much of its explanatory power in mandatory settings. Both attitude and intention are not good predictors of use. Data analysis also supported our hypotheses about information quality, a system characteristic important to the first-level informing instance, and net benefits from system use, which are the main objectives of informing at the second level of abstraction. We discuss the implications of our findings for system design, the fundamental activity at the third level of abstraction.Keywords: Mandatory software, user attitude, user satisfaction, information quality, system success, intention to use butok has authored over 100 journal articles, several book chapters, and more than 70 conference presentations in information systems measurement, quality control, risk assessment, and applied statistics.