Stockard Channing has been living with the formidable character of Ouisa Kittredge for 3 1/2 years - "a long, long while now," she says. From April 1990, when Channing first hit the boards as the flighty Manhattan upper-cruster of "Six Degrees of Separation," to just a few weeks ago, when she crisscrossed the States to thump the Fred Schepisi-directed film adaptation, a big chunk of the actress' life has been taken up thinking about - and being - the anecdote-dishing, name-dropping creature of John Guare's award-winning play.

The sole cast member to make the transition from stage to screen ("a stipulation of John's deal was that he wanted me to play the part"), Channing has brought to the film the same mix of amused awe and jaunty dramatics that won her a Tony nomination. "The trick for me was not to sacrifice the theatricality of the character, but not turn it into a stagy performance," explains Channing, in Philadelphia one day not long ago.The Ouisa of Guare's stage production and the Ouisa of the movie are, she says, on parallel courses: "Sometimes the performance would veer and sometimes it would match up, you know, like those highway maps where you see the old road and then the new road running alongside."

Inspired by a real-life incident - a young black man who conned his way into the lives of well-heeled New Yorkers by saying he was the son of actor Sidney Poitier - "Six Degrees of Separation" is a deft puzzle box that addresses some weighty issues (white liberal guilt, class conflict, racial and sexual stereotypes) without ever getting weighty itself.

Channing, 49, has known Guare since 1970 and says the writer "points flashlights on certain things, but ("Six Degrees") is not didactic in any way. It's not telling the audience who's good and who's bad."

With Donald Sutherland on board as Ouisa's husband, an international art broker forever teetering between insolvency and his next big deal, "Six Degrees" follows the Kittredges as they come under the spell of young "Paul Poitier" (played by a very able Will Smith), who appears at their door one night, claiming to have been mugged and claiming friendship with the Kittredges' away-at-college kids.

What follows is slyly funny and slyly tragic, an intricately woven tale that means . . . well, what exactly does it mean?