Who contributes the most to organizations? Employees working selfishly to benefit themselves, or employees working selflessly to benefit others?

Recent research reveals a surprising answer: neither. For starters, it turns out that in contrast to popular belief, self-interest and concern for others are not mutually exclusive. In a series of studies, psychologist Carsten De Dreu has documented that self-interest and concern for others are independent motives. And it’s a balance of the two motivations together, not purely selfish or selfless motivation, that drives the highest levels of effort and performance. Why?

Purely selfish motivation has downsides. When employees experience strong concern for themselves but not others, they only go the extra mile at strategic times. For example, researchers Chun Hui, Simon Lam, and Kenneth Law studied bank employees. Those who viewed helping as a path to getting promoted spent time helping their colleagues shortly before the promotion decision, but declined in helping afterward. Those who made no connection between helping and getting promoted maintained their efforts to assist their colleagues even after the promotion decision. Selfish motivation often discourages employees from taking initiative and helping others unless these activities are directly rewarded, which can be detrimental to their long-term performance, reputations and careers.

Purely selfless motivation also has drawbacks. When employees experience stronger concern for others than for themselves, they are in danger of self-sacrificing. In a study of professional engineers, researcher Frank Flynn found that although engineers gained respect from their peers for being highly generous, they paid a productivity price: those who spent a great deal of time helping colleagues achieved objective results that were lower in both quality and quantity. Selflessly motivated employees are willing to help others even when it is personally costly. This puts them at risk for burning out.

A blend of the two motivations helps employees minimize these risks, achieving more sustainable performance. In Flynn’s study, engineers were able to help colleagues without sacrificing productivity if they called in favors as well as granting them. A balance of giving and receiving enabled the engineers to complete high-quality, high-quantity work and support their peers.

Similarly, in two studies, psychologist David Mayer and I demonstrated that employees are most likely to go the extra mile when they care about both “doing good” and “looking good.” The desire to do good motivates employees to take initiative and help others. The desire to look good makes sure that they don’t burn themselves out in the process. To do good and look good at the same time, employees find ways to align others’ interests with their own. As a result, employees tend to work hardest, most creatively and most effectively when they’re aiming to benefit themselves and others at the same time.

As Bill Gates argued at the World Economic Forum: “This hybrid engine of self-interest and concern for others serves a much wider circle of people than can be reached by self-interest or caring alone.”