Every year, individuals and organizations end up adopting (licensing) many competing software products. Yet, over time, much of the adopted software remains unused because users forgo the use of one software product for another adopted alternative. Although much research in the IS field has examined initial IS adoption, less is known about such post-adoption behavior. This article argues that a sense of “technology commitment” to one technology over other adopted alternatives is key to sustained post-adoption use intentions. By forwarding a technology commitment model, this article investigates the antecedents of technology commitment and its consequent effects on IS continuance. In the model, the article also examines how technological inertia moderates IS continuance intentions. Gathering empirical evidence from IS continuance intentions related to Webmail services, findings from the study offer interesting insights into the mechanics of continuance.