Boycotts are among the most frequent forms of consumer expression against unethical or egregious acts by firms. Most current research explains consumers’ decisions to participate in a boycott using a universal cost-benefit model that mixes instrumental and expressive motives. To date, no conceptual framework accounts for the distinct behavioral motives for boycotting though. This article focuses on motivational heterogeneity among consumers. By distinguishing two stable behavioral models—a self-regarding type and a strongly reciprocal type—we introduce the notion of strong reciprocity to the boycott literature. We argue that the presence of strongly reciprocal consumers can enhance boycott success. First, in interactions with the target firm, strongly reciprocal consumers perceive higher levels of egregiousness and are more willing to engage in boycotting behavior, even in unfavorable strategic conditions, which provides a stable basis for boycotting. Second, in interactions with self-regarding consumers, strongly reciprocal consumers are willing to sanction those others, according to whether they participate in the boycott, which increases overall participation in and the likelihood of success of a consumer boycott. These findings have implications for further research, as well as for firms, nongovernmental organizations, and boycotters.