Many organizations have turned towards globally distributed software development (GSD) in their quest for cheap, higher-quality software that has a short development cycle. However, this kind of development has often been reported as being problematic and complex to manage. There are indications that trust is a fundamental factor in determining the success or failure of GSD projects. This article studies the key factors that cause a lack of trust and the effect of lacking trust and present data from four projects in which problems with trust were experienced. We found the key factors to be poor socialization and socio-cultural fit, increased monitoring, inconsistency and disparities in work practices, reduction of and unpredictability in communication; and a lack of face-to-face meetings, language skills, conflict handling, and cognitive-based trust. The effect of lacking trust was a decrease in productivity, quality, information exchange and feedback, morale among the employees, and an increase in relationship conflicts. In addition, the employees tended to self-protect, to prioritize individual goals over group goals, and to doubt negative feedback from the manager. Further, the managers increased monitoring, which reduced the level of trust even more. These findings have implications for software development managers and practitioners involved in GSD. Copyright © 2008 John Wiley & Sons, Ltd.