People engage in self-promotional behavior because they want others to hold favorable images of them. Self-promotion, however, entails a tradeoff between conveying one’s positive attributes and being seen as bragging. We propose that people get this tradeoff wrong because they erroneously project their own feelings onto their interaction partners. As a consequence, people overestimate the extent to which recipients of their self-promotion will feel proud of and happy for them, and underestimate the extent to which recipients will feel annoyed (Experiment 1 and 2). Because people tend to self-promote excessively when trying to make a favorable impression on others, such efforts often backfire, causing targets of the self-promotion to view the self-promoter as less likeable and as a braggart (Experiment 3).