When it comes to Chris Rock, it’s the gait above all. Sure, there’s the voice too, a purring rasp that never sounds at peace, and the eyes, which are emphatic and precise. But anyone who’s seen Rock walk the stage during one of his comedy shows knows his stride cold: the long, slightly jagged steps that seem to eat up the floor beneath him; the mild bop in his strut; the liquidity of his movement, as if he’s engaged in one very long motion, not hundreds of small ones.

So it’s noticeable when Rock, 46, walks into the Harlem restaurant Sylvia’s with small, quiet steps, as he did last month. A goatee shot out at an angle from his chin, and his head, from which no shortage of outlandish, blue insults have issued over the years, was tucked into a soft hat. This is Rock in repose.

And in re-evaluation mode too. For the last few weeks he has been learning how to walk a stage that’s not his to roam, in preparation for his Broadway debut in “The (BLANK) With the Hat,” (the title contains an obscenity), which begins previews on March 15. In the play — written by Stephen Adly Guirgis and directed by the Tony Award winner Anna Shapiro — Rock plays Ralph D., an irresponsible 12-step sponsor dodging his own demons by toying with those of his sponsee. He is a tragicomic character trapped in a maze of misrepresentations, and also a jerk.

Taking a breath

For Rock, known for his high-volume tirades on race and sex, it’s an opportunity to slow down, and also to not be in charge. Rock, committed to a four-month run, described Guirgis’ dark comedy, his first engagement with the theater apart from the 2007 installment of 24 Hour Plays, the annual stunt theater extravaganza, as “something I can be in, not be.”

That was crucial for Rock, for whom Broadway hasn’t been a lifelong dream. “There might have been two Playbills in my house, one of them was ‘Purlie,’” he said, referring to the 1970s Broadway musical. “I can’t say I looked at it the way I looked at stand-up.”

To make the transition he has needed to learn some new habits. “He paces the stage like a puma,” Shapiro said. “Now he’s learning to take that wide focus and make it a laser focus. He’s learning that the most important person onstage is his partner.”

Guirgis said, “If people are going to come for the stand-up routine, they’re going to be disappointed.” Instead what they’ll get is a signature Guirgis production, with rough-hewn characters who talk tough and also smart. There are laughs, but they’re mostly derived from tragedy and hostility, not necessarily Rock’s engines.

About acting in this play Rock said: “This is not for the arrogant. You thought you were humble until you started doing a play. Ten years ago I’d have probably got fired already, or I’d have quit, and they’d have been happy I quit.” (The producers may be protective of Rock, as a reporter was not permitted to watch rehearsals.) But Rock’s priorities have changed in the last 10 years. Once one of the most visible comedians in the country, he has been in slow retreat, his career cool since he hosted the Oscars in 2005. He has been the primary star of only two live-action comedies since 2001, when he starred in both “Down to Earth” and “Pootie Tang.” In 2003 there was “Head of State” and in 2007 “I Think I Love My Wife,” which he also directed and adapted (with Louis C.K.) from an Eric Rohmer movie. In between there have been ensemble pieces like “Death at a Funeral” and “Grown Ups,” and small parts in “You Don’t Mess With the Zohan” and others.

More notably, you often hear his voice, but that’s it, whether as the narrator of “Everybody Hates Chris,” the sitcom based on his childhood that ran from 2005 to 2009, or as the wily zebra Marty in the “Madagascar” movies, the third of which is filming now. “Animation is a gift from God,” Rock said. “Somebody gives you an animated gig and pays you, you did something nice to somebody along the way.”

But while the play might be moving up a weight class, Rock sees it as an opportunity for smallness. He marks up his script with questions and notes, eagerly asks questions of Shapiro and Guirgis and admits excitedly, “I’m definitely the low man on the totem pole, but I’ll be ready for opening day.”