As employees find themselves in geographically separated teams, the loss of face-to-face interaction has led to the development of new monitoring technologies that provide availability information for enhancing collaboration. Drawing on diverse literatures in electronic performance monitoring, computer supported cooperative work, privacy, and fairness, a comprehensive theoretical model of monitoring acceptance was developed to examine the effects of being monitored for availability. In the first study, over 600 employees from a large number of organizations responded to one of a variety of monitoring system characteristics. Although the model found strong support overall, results suggest that technical solutions, such as manipulating the characteristics of the awareness system, are not sufficient to ensure fairness and privacy. A second, focus group study, adds support for the theoretical model and provides an explanation for these quantitative results concerning system characteristics. Specifically, the qualitative evidence suggests that these systems can invade employees' psychological barriers - and thus manipulating the technology will only have small effects on fairness and privacy because the technology has already crossed the line from benign to invasive. The paper concludes by presenting theoretical and practical implications for the consideration of psychological boundaries in the design and use of ubiquitous monitoring and communication technologies. Copyright © 2002 John Wiley & Sons, Ltd.