Laura Osnes has just reached the halfway mark in her seven-month stint as Nellie Forbush in South Pacific, an experience that has been, she says echoing one of Nellie's lyrics, "a grand and a beautiful thing." So the other day in her dressing room, just before a matinee, I asked this native of suburban Minneapolis, who made her Broadway debut in Grease after winning a TV reality show, to talk a bit about the highs and lows of doing South Pacific.

"Overall, I think the job has been close to what I expected," Osnes said. "One thing I worried about was being able to cry every performance. It might sound kind of strange for me to say that. I mean, in Grease, my character, Sandy, cries in almost every scene: she's the underdog who's always being teased. But doing that was easy -- that was high-school sadness: 'My boyfriend left me.' With Nellie, the tears are about war and death - sorrow. Being able to get there emotionally takes preparation. I've learned that sometimes I need to stand backstage alone for two or three minutes before I go on to get to where I need to be."

Kelli O'Hara, Osnes' predecessor in the role, has spoken about the challenge of playing Nellie's racism. Osnes agrees that this aspect of the role isn't always easy. "I'm sometimes asked to play Nellie's racism with more anger. That's been something I've worked on. The text helps - she says the word 'colored.' And it helps me a lot that Nellie gets to redeem herself. But you have to make that change believable, and that's a challenge."

What about the musical demands of playing Nellie? "I knew that, relatively speaking, this role required a lot of singing," replies Osnes, whose training was in musical theater, not in opera like her costar Paulo Szot. "Luckily, the music sits in a comfortable place in my voice," she added. "Grease was more vocally taxing, because the notes went higher and because I had to belt."

Osnes continued: "In spite of 'Honey Bun' and 'Wash That Man,' singing Nellie is not primarily about showing off. Her first number is 'Cockeyed Optimist,' which ends in a very anti-climactic way. I'm fascinated that Rodgers & Hammerstein introduce her in such a quiet fashion, and in a long opening section that is the hardest scene for me, because we have to establish so much of the story there."

Osnes credits a large group of people for assisting her to meet the demands of playing Nellie every night. She mentions the show's director, Bartlett Sher: "He helped me in innumerable ways." And the stage manager, Michael Brunner: "We'd all die without him." And her costar, Szot: "So gifted." And the whole South Pacific cast: "It was intimidating coming in as the new girl, but everyone here is so friendly."

But Osnes, who occasionally made specific points during our interview by pointing to photographs of friends and family and backstage visitors on her dressing-room wall, seems to reserve some special emotion for her grandmother, whose framed photograph Osnes can see every night as she puts on her makeup.

"My grandma was a nurse. She graduated just after the war. But she had a lot of friends who had gone off and been killed in the conflict. If I'm having a day where I don't feel completely up to doing the show, I look at her picture or at pictures of nurses and soldiers who were in the war. That helps restore me. My grandma lives in Iowa and is coming to see South Pacific in July. I can't wait."

BRENDAN LEMON is the American theater critic for the Financial Timesand the editor of lemonwade.com.