A few days before opening in “Sabrina Fair” at Ford’s Theatre last fall, Susan Heyward found herself bawling in front of the cast.

“At first I didn’t understand why I couldn’t stop crying,” Heyward says in an interview from New York. Heyward was playing the lead — the Audrey Hepburn part, if you think of the movie “Sabrina” — in Samuel A. Taylor’s 1953 Cinderella romance. Chauffeur’s Daughter Captures Heart of Rich Employer’s Son, goes the story, only Ford’s made the play about race by isolating Sabrina and her father as black figures in an affluent white milieu.

The script itself remained unchanged. But even though the characters did not mention the new theme, it was blatant.

“It hurt so much to be in a world where something so elemental to your being was ignored,” Heyward says, explaining her sudden eruption. “I had to acknowledge that for Sabrina.”

There may be power yet, then, in an idea that last seemed vanguard a couple of decades ago: nontraditional casting. Latinos, blacks and whites in Arena Stage’s “Oklahoma!” last fall, and now an African American version of Horton Foote’s 1953 “The Trip to Bountiful” at Bethesda’s Round House Theatre. The concepts don’t necessarily seem fresher than Arena’s “Pygmalion” with an African American Eliza Doolittle 20 years ago or an all-black “Waiting for Godot” on Broadway in 1957.

But Timothy Douglas, director of “The Trip to Bountiful” (best known as the 1985 film that won Geraldine Page the Academy Award for Best Actress), suggests that nontraditional casting is enjoying a renaissance. The flurry on Broadway in recent seasons has included Morgan Freeman in Clifford Odets’s “The Country Girl,” S. Epatha Merkerson in “Come Back, Little Sheba” and an all-black “Cat on a Hot Tin Roof” — all 1950s plays, curiously, like “Bountiful.”

“I don’t think we’re beyond it,” says Douglas, adding that the notion of the Obama era as post-racial is fantasy. “There is this other huge section, and I belong to it, that says no, the conversation just begins. So, on that level, nontraditional casting has a potential for even greater impact now.”

The gambit is never wholly free from controversy, though. “Sometimes,” suggests actor Howard Overshown, who plays the son of the aging woman who longs to return home in “Bountiful,” “I feel nontraditional casting is in lieu of doing black plays.”

Indeed, the theater world still has to contend with the long shadow of August Wilson’s 1996 speech railing against colorblind casting as a form of “assimilation” (his word) to be resisted. When Arena convened a national panel of black playwrights last winter, Wilson’s speech was handed out as the starting point for the conversation.

“It is an assault on our presence,” Wilson thundered, complaining of a theoretical all-black “Death of a Salesman,” “an insult to our intelligence” and “our playwrights. . . . We do not need colorblind casting; we need some theaters to develop our playwrights.”

Edward Albee, who has long been outspoken about sticking to the playwright’s intentions, issued a general caution on nontraditional casting as the current festival of his works was being put together at Arena. When Ford’s director, Paul Tetrault, told the “Who’s Afraid of Virginia Woolf?” author about his concept for “Sabrina Fair,” Albee replied, “Do you think that black people and white people are completely interchangeable?’”

The answer in “Sabrina Fair,” “Oklahoma!” and “Bountiful” seems to be: of course not. But almost. Sometimes. And as with the tears that hit Heyward out of the blue, the artists can’t always predict the ramifications or anticipate each result.

“I’m not sure,” says Arena artistic director Molly Smith when asked why the cross-cultural casting of her “Oklahoma!” was seen as a progressive affair, while Arena’s racially mixed 1999 “Guys and Dolls” with Maurice Hines was not.

“That had not come into my consciousness,” Douglas says in response to the assertion that doing a “white” play with black actors often takes one of the limited programming slots that might have gone to a black playwright.

Smith (who is white, as is Tetrault) and Douglas (who is black, and who takes over Chicago’s Remy Bumppo Theatre Company this summer) are experienced in the risks and rewards of nontraditional casting, yet it’s clearly a challenge to articulate standard practices even decades into the broad and deep lowering of casting barriers.

Race frequently stands for little in contemporary productions of European classics; just check your most recent Shakespearean playbill, no matter where you’ve been. “Colorblind” is the term for casting in those cases, and Tetrault uses it to explain the policy of his theater’s annual production of “A Christmas Carol”: “We’ll cast anyone in any role,” he says.

Lizan Mitchell, who is playing the homesick Carrie Watts in “Bountiful” at Round House, has appeared in Greek tragedies in which race was immaterial. It’s the American plays that up the ante, she says.

“History comes with it,” Mitchell notes.

Douglas, who chose “Bountiful” because it represented a juicy part for Mitchell, thinks calibrating that historical freight is critical. “Does the collective lack of healing around race relations in America push the play over the edge?” he asks. “Can the play handle it? Or will it collapse underneath it?”

Even then, audiences may choose to ignore what’s being provoked by careful casting (Smith likes the phrase “cross-cultural casting” for the calculated relations she chooses to depict). Heyward, who says she enjoyed doing “Sabrina Fair” but wishes it could have pushed the concept a little harder, reports that there were evenings, usually in front of majority-white audiences, when “Sabrina Fair” sparked no racial frisson.

“Some nights we were just, ‘OK, I guess we’re doing a splashy romantic comedy tonight,’ ” she recalls. With a largely African American audience, though, “You could feel that they brought their own stories with them. Things that went unsaid, they noticed that they went unsaid. It had more of the danger we were looking for.”

Thus black dramatists have been known to hold up a hand and say: Hey, if you want to send a less ambiguous message, we have a couple of scripts you could look at.

At the same time, Overshown argues that theater is far more hospitable to writers of color than it was when Wilson made his intensely debated speech. And he flew straight into the teeth of one of Wilson’s biggest claims as part of the 2009 all-black “Salesman” cast at Yale Repertory Theatre.

That “Salesman” starred old Wilson hands Charles Dutton and Kimberly Scott — “two seasoned actors who had been there with August from the beginning, now doing amazing performances,” Overshown says. “And they’re the ones who wanted to do it.”

Still, Wilson’s complaint about white-run theaters picking the plays and seldom drawing deeply from the black repertoire remains a problem. Smith and Tetrault are comfortable pointing to their companies’ track records producing black writers, but Mitchell — who says she often participates in readings of promising new plays that never get produced, to say nothing of the rarely touched canon of African American works — is troubled.

“The value that is being missed because of this is a travesty,” Mitchell says. “Life comes from a very small stream of knowledge. If all you’re seeing is one kind of play, then there’s a vast part of life that you haven’t been exposed to at all.”

Not that she thinks actors of color should hold out exclusively for roles written by black, Asian, Hispanic or Native American playwrights. “You don’t automatically refuse anything,” she says. “You have to see what is of value to you, and what is of value to people who are listening and expecting something.”

Mitchell, who played Carrie Watts for a month in Cleveland and inhabits the role through April 3 here, adds a final, personal, practical criterion: “Am I gonna have a good time doing it,” she laughs. “For real.”