We develop a model of fragile self-esteem — self-esteem that is vulnerable to objectively unjustified swings — and study its implications for choices that depend on, or are aimed at enhancing or protecting, one’s self-view. In our framework, a person’s self-esteem is determined by sampling his memories of ego-relevant outcomes in a fashion that in turn depends on how he feels about himself, potentially creating multiple fragile “self-esteem personal equilibria.” Self-esteem is especially likely to be fragile, as well as unrealistic in either the positive or the negative direction, if being successful is important to the agent. A person with a low self-view might exert less effort when success is more important. An individual with a high self-view, in contrast, might distort his choices to prevent a collapse in self-esteem, with the distortion being greater if his true ability is lower. We discuss the implications of our results for mental well-being, education, job search, workaholism, and aggression.