When is employee retaliation acceptable in the workplace? We use a quasi-experimental design to study the acceptability of several forms of retaliatory behavior at work, gathering data in this untested area. Consistent with hypotheses from theories of fairness, we find that employee retaliation in the workplace is perceived to be more acceptable if it is an act of omission instead of an act of commission. We do not find that a more damaging retaliatory act is significantly less acceptable than a less damaging one, suggesting a qualitative rather than a quantitative relationship. We also find individual differences: Respondents who are older, female, politically conservative, and managers typically show less tolerance for retaliation, while union members are a bit more accepting than average.