During his Mobile World Congress keynote earlier this week in Barcelona, Facebook CEO Mark Zuckerberg spoke about his Internet.org initiative, his relationship with telecom operators and expanding Internet access. But what has seemed to grab just as many headlines was a nugget of management wisdom he shared during a public town hall question and answer session on Wednesday.

In response to a question about what he looks for when selecting employees, Zuckerberg said he always poses one simple question to himself when he hires a direct report: Would he be willing to work for that person, if the roles were reversed?

"I`ve developed over time a simple rule," he told the audience. "I will only hire someone to work directly for me if I would work for that person. And it`s a pretty good test."

He was quick to say that doesn`t mean he`s looking for someone to replace him. "It doesn`t necessarily mean that I`m rushing to give up my job of running the company and put other people in the role," Zuckerberg said. "But what it does mean is that in an alternate universe—if things were different and I didn`t start the company—I would be happy to work for that person."

That basic test isn`t just something for executives, Zuckerberg added. "If you`re building a big organization, then it also works many layers down. If each person is only hiring people to work directly for them who they would work for, then you`re probably going to get a pretty strong organization."

Zuckerberg explained that this is a challenge that all growing companies face, big or small, as they deal with the pressures of growing and dealing with the ever-expanding amount of work. It "leads you to want to get people in to help you out and do that work, even if they`re not the very best people. So one of the things that you always need to be very careful about is having a check in place, so that you only really hire the best people despite this pressure," he said. "Over the long term you`re really only going to be better off if you get someone really good."

It`s smart advice, of course, but it`s also perhaps easier for Zuckerberg to say than others. Not every CEO, after all, runs a company that has the same kind of resume wattage to choose from, and the same level of cushy Silicon Valley benefits to offer them.

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