Women have long surpassed men in the arena of environmental action; across age groups and countries, females tend to live a more eco-friendly lifestyle. Compared to men, women litter less, recycle more, and leave a smaller carbon footprint. Some researchers have suggested that personality differences, such as women’s prioritization of altruism, may help to explain this gender gap in green behavior.

Our own research suggests an additional possibility: men may shun eco-friendly behavior because of what it conveys about their masculinity. It’s not that men don’t care about the environment. But they also tend to want to feel macho, and they worry that eco-friendly behaviors might brand them as feminine.

The research, conducted with three other colleagues, consisted of seven experiments involving more than 2,000 American and Chinese participants. We showed that there is a psychological link between eco-friendliness and perceptions of femininity. Due to this “green-feminine stereotype,” both men and women judged eco-friendly products, behaviors, and consumers as more feminine than their non-green counterparts. In one experiment, participants of both sexes described an individual who brought a reusable canvas bag to the grocery store as more feminine than someone who used a plastic bag—regardless of whether the shopper was a male or female. In another experiment, participants perceived themselves to be more feminine after recalling a time when they did something good versus bad for the environment.