Online reviews are vital for e-commerce, yet motivating consumers to write them remains challenging. While financial incentives are commonly used, they can crowd out altruistic motives, leading to suboptimal outcomes. Drawing on Social Exchange Theory, this study examines how the beneficiary of altruism (the company vs. other customers) moderates the impact of incentives on review-writing decisions. We test our hypotheses in a quasi-experimental field study in collaboration with a major North American online retailer and a controlled experiment. Our findings show that reinforcing altruism through helping the company negatively interacts with financial incentives compared to helping other customers. We contribute to the literature on altruism, Social Exchange Theory, and eWOM creation and propose a cost-effective and straightforward modification to review solicitation messages to boost review volume.