This Article presents results from three experiments offering evidence that parties see breach of contract as a form of exploitation that makes disappointed promisees into Suckers. In psychology, being a sucker turns on a three-part definition: betrayal, inequity, and intention. We used web-based questionnaires to test the effect of each of the three factors separately. Our results support the hypothesis that when breach of contract cues an exploitation schema, people become angry, offended, and inclined to retaliate even when retaliation is costly. This theory offers a useful advance because it explains why victims of breach demand more than similarly situated tort victims and why breaches to engorge gain are perceived to be more immoral...