Incivility is an interactive event where the target, the instigator, and the situation play a role. Research has not yet examined what actually triggers employees to act in an uncivil manner and how targets and witnesses respond to uncivil behaviour. It has been suggested, though, that targets and witnesses of workplace incivility may react with equal or harsher deviant behaviours toward the instigator or others in their environment and that uncivil incidents at work could ultimately result in a spiral of increasingly deviant and aggressive behaviour. However, because uncivil incidents are relatively mild and characterised by the ambiguous intent to harm the target, targets and witnesses may have difficulty making sense of the situation and how to perceive the uncivil incident. Hence, individuals may differ in their perceptions of and reactions to uncivil incidents, depending on their causal attribution of the instigator’s uncivil behaviours. The current study will examine these issues— what triggers workplace incivility, what are the causal attributions targets and witnesses make for instigators’ uncivil behaviour, and how do they actually respond to it.