Research has long shown that using friendly nicknames can be a great way to solidify personal relationships between peers or romantic partners. But what’s the impact of using nicknames in professional environments, in which power disparities are common? Through a series of studies with more than 1,100 U.S.-based adults, research finds that using nicknames in workplace relationships between supervisors and subordinates can sometimes have positive effects — but not always. Specifically, researchers found that when employees can call their supervisors by a nickname, they feel more psychologically safe, more powerful, and more respected by their boss — but when supervisors call their subordinates by a nickname, employee wellbeing suffers. This effect is stronger in organizations with strong hierarchical cultures. This research suggests that managers and senior leaders should allow others to call them by their nicknames, but when it comes to calling a junior employee by a nickname (even a well-intentioned one), managers should exercise caution.