This paper empirically investigates the determinants of willingness to do good of green investment within a real-world context. Using data from a questionnaire administered between December 2021 and January 2022 to French individual investors, we find that “being good” (altruism) and “acting for good” (perceived impact) exert a substantial influence on both the decision-making process and the amount invested in green funds, while positive emotions (warm glow) are not significantly linked. This research highlights the core importance of altruism in green investment decision.