As competing technological choices emerge in the marketplace, an inevitable consequence is user switching from one IT product or service to another. However, we know very little of this phenomenon or the key drivers of user switching. We examined the reasons for IT switching by proposing a model that synthesized and extended current theories of IT acceptance and customer satisfaction. We believed that IT switching was driven by user dissatisfaction with an incumbent product or service and the fact that the customer was aware of the availability of a potentially superior product or service. Further, to explain differential switching patterns across an adopter population, we posited personal innovativeness as an individual difference variable that moderated the effect of user dissatisfaction and relative advantage of a new IT on users’ switching intention. Our model was empirically validated using a longitudinal survey of web browser switching among student subjects. We hope that our study will generate researchers’ interest in an understudied area of research and that the model will serve as a starting point for furthering our understanding of IT switching