According to the Harvard Business Review, women and people of colour in leadership roles are penalised for trying to diversify the workplace. White men are not.

Stephanie K Johnson and David R Hekman write that 85% of corporate executives and board members are white men—and that the proportion hasn’t changed for decades. The authors suggest that this is because white men keep choosing and promoting other white men. They did a study. They found that diversity-valuing behaviour results in diminished performance ratings for women and people of colour.

We seek to help solve the puzzle of why top-level leaders are disproportionately white men. We suggest that this race- and sex-based status and power gap persists, in part, because ethnic minority and women leaders are discouraged from engaging in diversity-valuing behavior. We hypothesize and test in both field and laboratory samples that ethnic minority or female leaders who engage in diversity-valuing behavior are penalized with worse performance ratings; whereas white or male leaders who engage in diversity-valuing behavior are not penalized for doing so. We find that this divergent effect results from traditional negative race and sex stereotypes (i.e. lower competence judgments) placed upon diversity-valuing ethnic minority and women leaders. We discuss how our findings extend and enrich the vast literatures on the glass ceiling, tokenism, and workplace discrimination.

This tendency towards like-promotes-like occurs in many spheres beyond the corporate world—for example, academia, publishing, and politics—and to other discriminated-against groups.

We are all allies. Even those of us who belong to several oppressed groups have, in some situations, rank and power that some others don’t. Perhaps we’re able-bodied. Perhaps we’re straight. Perhaps we’re white. Perhaps we had a decent education, or have a fabulous income, or married. Rank, power, and privilege is always relative. In any given situation sometimes we have more, sometimes we have less. If we have more, we can be allies of those who have less.

As allies we need to step up on others’ behalf. This study shows that those who are being discriminated against are likely to be devalued for trying to change that; those who have rank and power are not.

My business is mainly books. Today that’s my focus. Here are five suggestions for what allies can do in the next month:

That’s just off the top of my head. There are many, many ways to support diversity. These range from occasionally saying something, to not using thoughtless language, to giving time or money or attention. The more rank, power, and privilege you have as an individual or a group member, the more opportunity you have to help. No matter who you are you will find some situations where you have more heft and influence than others. So step up, speak out, put your money where your mouth is. Do what you can. Make a difference.