The current research examined the effectiveness of two social influence strategies—reciprocity and social validation—in promoting sustainable consumer behavior. In an initial behavioral field experiment (Study 1), consumers were either exposed to a reciprocity, social validation, or control message distributed in the changing rooms of a sporting goods store. The daily number of cleanups carried out by store employees were then monitored as a function of message type. Results revealed that messages based on reciprocity and social validation led to a significant reduction in the number of cleanups compared to the control message, with no significant difference between the reciprocity and social validation conditions. In a follow-up online experiment with increased rigor and control (Study 2), participants were randomly assigned to a reciprocity, social validation, or control condition and subsequently indicated their willingness to shop sustainably. Consistent with the findings from Study 1, both the reciprocity and social validation conditions outperformed the control condition regarding participants’ willingness to engage in sustainable consumer behavior, with no significant difference between the reciprocity and social validation conditions. Together, this research suggests that the strategic use of reciprocity or social validation messages can help store managers reduce the environmental impact of consumers’ shopping responses, while simultaneously decreasing operating costs.