Counterfactual thinking is the process of mentally undoing the outcome of an event by imagining alternate antecedent states. For example, one might think that if they had given up smoking earlier, their health would be better. Counterfactuals are more frequent following negative events than positive events. Counterfactuals have both aversive and beneficial consequences for the individual. On the one hand, individuals who engage in counterfactual thinking experience negative affect and are prone to biased judgment and decision making. On the other hand, counterfactuals serve a preparative function, and they help people reach their goals in the future by suggesting effective behavioral alternatives. Counterfactual thoughts have been found to influence an array of cognitive processes. Engaging in counterfactual thinking motivates careful, in-depth information processing, increases perceptions of self-efficacy and control, influences attitudes toward social matters, with consequences for behavioral intentions and subsequent behaviors. Although it is a heavily studied matter in some domains of the social sciences (e.g., psychology, political sciences, decision making), counterfactual thinking has received less attention in the communication discipline. Findings from the few studies conducted in communication suggest that counterfactual thinking is a promising message design strategy in risk and health contexts. Still, research in this area is critically needed, and it represents an opportunity to expand our knowledge.