For organizations to achieve the benefits of new information technology (IT) systems, their users must adopt and then actually use these new systems. Recent models help to articulate the potentially different explanations for why some users will adopt and then continue using new technologies, but these models have not explicitly incorporated IT knowledge. This is particularly important in contexts where the user base may be non-IT professionalsÑi.e., the users may vary substantially in their basic IT knowledge. We draw on psychology to argue that in situations where there is a wide variance in actual IT knowledge, there will often exist a U-shaped relationship between actual and self-perceived IT knowledge such that the least knowledgeable believe themselves to be highly knowledgeable. We then draw on individual-level adoption theories to argue that users with high self-perceived IT knowledge will be more likely to adopt new technologies and do so faster. We also draw on individual-level continuance theories to argue that users with low actual IT knowledge will be more likely to discontinue using new technologies and do so faster. We test our expectations using a proprietary data set of 225 sales professionals in a large Indian pharmaceutical company that is testing a new customer relationship management system. We find strong support for our hypotheses.