"Clybourne Park" is the fiercest, frankest, funniest discussion of race I have seen on a stage. It is smooth — taut, realistic and stringing together ideas about real estate and racial perceptions. Its playwright, Bruce Norris, is a skillful manipulator who mines an audience's willingness to self-indict, provoking theatergoers with mouth-dropping lines and making them laugh at the same time.

The show, almost surely en route to a Tony Award as best new play this season, offers up two eras of American life a half-century apart — 1959 and 2009 — to suggest that although the idea of diversity has taken hold and brought many changes, not much has changed in the basic way people think about race. Yet "Clybourne Park" is anything but cynical. Mostly, it's revealing.

The play, set in the same Chicago house that figured in Lorraine Hansberry's groundbreaking 1959 play "A Raisin in the Sun," premiered two years ago Off-Broadway at Playwright Horizons, then hit London, Washington, Toronto and Germany. It won London's prestigious Olivier Award, and last year's Pulitzer Prize for drama.The cast on Broadway has come from a production in Los Angeles, staged at the same time Philadelphia's Arden Theatre Company was running its own.

The Arden's version, directed by Ed Sobel, came off a bit differently than the Broadway production, which opened Thursday night. The second act — when Norris really lets loose with his characters' intimations about racial issues surrounding the sale of a property to a white couple in a solid and upscale African American neighborhood — is mined more for laughs on Broadway, where it's directed by Pam MacKinnon. The Arden's production, while undeniably funny, was more intense as it progressed, giving the issues at stake a higher focus.

While that's the interpretation I prefer, there's nothing awry about the show on Broadway, where it provides all the food for thought and lets you do the grazing by yourself. "Clybourne Park" is a riff on what might have happened before and after the plot of Hansberry's "A Raisin in the Sun,"a play about a black family putting money down on a house in Chicago's all-white Clybourne Park neighborhood after World War II. The first act takes place in the house that the black family in "A Raisin in the Sun" will want to buy, as a white family prepares to move out. By the second act of "Clybourne Park," the neighborhood has become a gentrifying middle-class and largely black enclave, and a suburban white couple is trying to buy the property.

To appreciate "Clybourne Park," you needn't know anything about Hansberry's play, but understanding that one character in the first act and a minor discussion in the second act are directly related to "Raisin" makes "Clybourne Park" all the more rich. Still, I wish Broadway had found a way to present the play as Los Angeles' Center Theater Group did this winter: "Clybourne" in one theater while "Raisin" played in another.

For a short while, it looked as if the Broadway-bound run of "Clybourne Park" would end in Los Angeles. Its Broadway producer, Scott Rudin, was put off after the playwright, who is also an actor but no longer wants to be, opted out of performing in a pilot Rudin was about to produce for HBO. Rudin canceled the Broadway run. But the Jujamcyn Theater company, which owns five Broadway houses including the one in which "Clybourne Park" was booked, took up the banner by becoming the new lead producers for the play, and puttogether a group of backers to get it to Broadway.

Both acts of Norris' play evolve into a discussion about race, with whites and blacks on stage at the same time. The same cast plays different roles in each of the two acts on Daniel Ostling's set, a spacious living room that becomes a run-down one in Act 2, and ripe for a makeover. The makeover becomes an issue as community leaders, a lawyer and the white couple set on buying the property meet in the living room to hash out zoning issues. The situation is exacerbated by the new owners' plans to tear the place down and build anew, 15 feet higher than anyone else on the block.

The cast is uniformly excellent — Crystal A. Dickinson and Damon Gupton as a maid and her husband in Act 1 and married community leaders later on, and Frank Wood and Christina Kirk as the white couple selling the house in 1959 and in other roles later. Annie Parisse and Jeremy Shamos are the white couple moving in 2009, and Brendan Griffin is a preacher caught in the middle in Act 1, and all three switch roles, also.

There's a lot of heated and funny talk in "Clybourne Park," some of it graphic and some of it shrouded in language that doesn't say what it really means. Whether you're a character on the stage or a member of the audience, what's really being said is painfully clear, even — or maybe especially — through the laughter.

Contact Howard Shapiro at 215-854-5727 orhshapiro@phillynews.com, or #philastage on Twitter. Read his recent work at go.philly.com/howardshapiro. Hear his reviews at the Classical Network, www.wwfm.org.

"Clybourne Park" is at the Walter Kerr Theatre, 219 W. 48th St., New York.