One of these days you’re going to become the big wheel in the office. When you do, here’s some advice: Go back and reread Shakespeare’s Henry IV.

As you may dimly recall from high school, it’s the story of young Prince Hal’s ascent to the throne. At first he’s just another slacker partying with Falstaff and his gang of pre-Renaissance yahoos. But as soon as he’s crowned king, Hal transforms himself: He disavows his former posse, banishes Falstaff, and—for good measure—starts banging the drums for a war with France.

The lesson is that even when you’ve snagged the most powerful job in your office, you need something more: Respect. Loyalty. Maybe even a bit of fear. And it isn’t enough merely to slap the brass BOSS nameplate on your door. To establish your mojo, you’ll have to perform one powerful, symbolic act—ideally in the first few days on the job-—that will instantly prove that you are not to be trifled with. Consider it the art of the bold move—and if you really want to hold the reins at work, you’ll need to master it.

Top-shelf CEOs do this all the time. Last March, Mark Hurd took control of Hewlett-Packard after the long-serving CEO, Carly Fiorina, was forced out. Right out of the gate he canned nearly 15,000 people and announced that HP would no longer ship iPods— reversing one of Fiorina’s most high-profile deals. New IBM head Sam Palmisano’s opening gambit was to shred the upper management of Big Blue, a company notoriously resistant to change.

But let’s look at some more mortal leaders who’ve mastered the sort of corporate jujitsu you’ll need to pull off. One guy I know—we’ll call him Richard—needed a bold stratagem to stave off a workplace crisis of confidence. He’d been hired to launch a splashy new magazine, but the preexisting art director was an incompetent flake. The problem was, Flaky was also a dear old friend of the magazine’s founder. The staff were in a state of nervous despair, and when they’d walk past Richard’s door whispering, he could see the doubt in their eyes: Who wears the pants in this office?

There was only one way to answer that question: Whip it out. Richard hauled the art director into his office and axed him. When he gathered his staff together to announce the execution, Richard could see that his employees regarded him with new respect—that combination of admiration and fear that forms the calculus of all workplace loyalty.

“When you’ve got a situation and everyone’s looking at you, you’ve got make a move,” he says.

What you’re trying to do, ultimately, is change the way other people see you. That can be particularly difficult if you’ve slimed up the greasy pole inside a company, because then you’re put in charge of guys you used to grab after-work martinis with. So when you become the big kahuna, experts say, one crucial symbolic move is psychological: transforming yourself from friend to boss.