While boycotts are increasingly relevant for management decision-making, there has been little research of the individual's motivation to boycott.Drawing upon the helping behavior and boycott literatures, the authors take a cost-benefit approach to the decision to boycott and present a conceptualization of motivations for boycott participation. Their framework was tested during an actual boycott of a multinational firm that was prompted by factory closings. Consumers who viewed the closures as egregious were more likely to boycott the firm, though only a minority did so.Four factors were found to predict boycott participation: the desire to make a difference, the scope for self-enhancement, counter-arguments that inhibit boycotting, and the cost to the boycotter of constrained consumption.Further, self-enhancement and constrained consumption were significant moderators of the relationship between the perceived egregiousness of the firm's actions and boycott participation. The role of perceptions of others' participation was also explored. Implications for marketers, NGOs, policymakers and researchers are discussed.