["Journal of Management Studies, EarlyView. ", "\nAbstract\nAccording to strategy research, firms with more narcissistic CEOs and firms with women CEOs exhibit better environmental performance (EP); however, we propose that better EP is unexpected when jointly considering these characteristics. Although positive attention theoretically drives more narcissistic CEOs' EP, by considering the gendered factors influencing CEO cognition and behaviour, we propose that this effect reverses for women. We develop and validate a novel, earnings‐call‐based machine learning measure of CEO narcissism (which we also compare with existing measures by Chatterjee and Hambrick 2011, Administrative Science Quarterly, 56, 202–207 and Petrenko et al. 2016, Strategic Management Journal, 37, 262–79) to test how CEO sex, narcissism, and positive attention shape EP. We triangulate evidence supporting our hypotheses from S&P 1500 firm panel data (Study 1) and an experiment with strategic leaders (Study 2): when EP generates more positive media attention, more narcissism negatively (positively) affects EP with women (men) leaders. Advancing a more precise understanding of how CEO narcissism affects EP for men and women CEOs, we explain the mixed effects of CEO narcissism and CEO sex in separately developing literatures; we also contribute to the microfoundations of (environmental) strategy with important implications for scholarship and practice while also mitigating measurement constraints in understanding the relations between CEO narcissism and firm action.\n"]