This study sheds light on how shocks, or events perceived as jarring, cause users to discontinue a service. We use image theory to develop a model of discontinuation (MOD) which includes five main concepts: shock, script, image violation, service and task dissatisfaction, and search for and evaluation of superior alternatives. MOD explains how two types of user discontinuation behavior—quitting and switching— are formed along seven paths that are either related to contextual or technological shocks or result from dissatisfaction with a task or service. Our first empirical study shows that more than 95% of the 467 ex-users surveyed followed one of these paths when discontinuing media streaming, social networking, and matchmaking services. In the second study, we developed a research model based on the MOD to understand how the psychological factors associated with shocks lead to the intention to discontinue. We evaluate this model with a scenario study in which we present the situation of users of a matchmaking service and present participants with a contextual shock. Data from 201 individuals show that users are likely to develop intentions to quit when they use an engaged script or experience an image violation. Interviews with a panel of practitioners confirmed that MOD provides a useful and applicable approach to understanding users' quitting and switching behaviors in different contexts. We conclude our paper with a discussion of implications for research and practice.