Funny how straightforward Rhonda Vincent sounds proclaiming herself an "All American Bluegrass Girl" in the song of that title—until you listen past the hook. The rest of the lyrics sanguinely argue that what she has going for her—musical talent, longtime devotion to the genre, a bluegrass family background—trumps how she diverges from bluegrass tradition as a mandolin-picking, lead-singing woman who's not from the South. Witness verse two: "All my life they told me / 'You're pretty good for a girl / Some day you'll play the Opry just like Sonny, Bob and Earl.' "

She is, and she has. Vincent is by far one of the best-known names and voices in bluegrass this decade. In 2006, the same year she released "All American," she was named the International Bluegrass Music Association's Female Vocalist of the Year for the seventh time in a row. She and her band, the Rage, won the IBMA's premier award, Entertainer of the Year, in 2001. (Incidentally, her brother Darrin Vincent did the same last year with his phenomenally matched duo Dailey and Vincent—and they might just repeat this year.)

Then there's Sierra Hull, a native of Byrdstown, Tenn., who's in her late teens. She's been turning heads at bluegrass festivals for a long time, and released her debut, Secrets, on Rounder last year. She, too, plays mandolin and sings, and she's nominated for some sizable IBMA awards: Emerging Artist and Instrumental Performer of the Year for mandolin. (She'd be the first woman to win the latter.) For Hull to find herself here so early in her career—especially since she used to be, as she puts it, "a lot of times the only female around" at weekend bluegrass jams—is no insignificant (or coincidental) thing.

"I remember seeing a Rhonda Vincent CD in Wal-Mart one time, and then it kind of dawned on me," she says. "I was like, 'Wow, a woman holding a mandolin.' I thought, 'Man, that'll be me someday.... I'll be grown and be a woman and be a mandolin player.' And then I thought about how unusual that was to really see that."

It's unusual because at the genre's inception—and for decades after—women were relatively scarce. "It's actually pretty astounding when you think the first bluegrass band was put together in 1945 by Bill Monroe, and it was basically five guys," says Alison Brown, a virtuosic, jazz-influenced banjo player and the first female winner in any IBMA instrumentalist category. "And bluegrass music continued to be basically five guys with very few exceptions until probably, like, the '90s things started to really change. So that was a long history—45 years."

Dale Ann Bradley, a two-time IBMA Female Vocalist of the Year, grew up in rural Kentucky in the '70s. "There weren't any female musicians in this area that I knew of," she says. "And that was a lot of years playing here and nobody ever surfaced, fiddle players or anything. The first real, I guess, idea that I had that girls could do anything they wanted to musically was the New Coon Creek Girls. That was probably '84." (She later joined the group, which was named for the original Coon Creek Girls, an all-female string band who performed a rustic-themed act on the Renfro Valley Barn Dance in the '30s and '40s.)

There are plenty of theories about why so few women played and sang bluegrass early on. Mary A. Bufwack and Robert K. Oermann, in their tome Finding Her Voice: Women in Country Music, 1800-2000, point to "emphasis on instrumental flash, aggressive vocals, and conservative social structure," plus the difficulty women faced balancing touring and homemaking. Brown notes that traditionally, women's work kept their hands busy, but men could more easily pick up an instrument after their work in the fields and factories was done.

So how did women eventually break the bluegrass ceiling? Bufwack and Oermann suggest the '60s folk revival got college women playing acoustic instruments. Murphy Henry—banjo player, onetime publisher of the "Women in Bluegrass" newsletter and author of a soon-to-be-finished book on the subject titled Pretty Good for a Girl—seconds that: "Folk music wasn't bluegrass, but it was acoustic music. And I think a lot of women saw that, liked it, learned to play guitar and then it was a short hop to bluegrass."

Henry also takes into account big-picture social progress: "So were guys resistant to women playing? I guess the facts would sort of show that, too, since women weren't there. But I guess I would have to say...culturally, that certainly does seem to parallel a lot of fields that now have women in them—anything from firefighters to police officers to doctors, stereotypically male. And women had to make inroads."

The presence of female pickers and singers is one thing. It's another for some—like Alison Krauss, Vincent, Brown, Bradley and, probably soon, Hull—to be as big in the bluegrass world as their male counterparts. Brown first made a name for herself in Krauss' band, and she pinpoints that period as a watershed: "I kind of feel like when Alison Krauss began to get the CMT and country music attention that she did, probably on her third record [I've Got That Old Feeling], I think that's really when the doors opened a little bit more for women, because, to my ear, I think that hearing a woman's voice singing bluegrass makes it more accessible to more people than the traditional high lonesome male voice."

On the subject of female voices, this year's slate of IBMA Female Vocalist nominees covers the spectrum. There's veteran singer Claire Lynch, whose new album, Whatcha Gonna Do, isn't strictly bluegrass so much as folk nudged toward pop, blues and traditional country. She and Bradley, who claims Lynch as an influence and has a new album of her own, Don't Turn Your Back, have honeyed, soft-edged voices. Vincent, Sonya Isaacs (part of the gospel-singing Isaacs family) and Alecia Nugent—who's the youngest of the bunch and released her third album, Hillbilly Goddess, this year—have brighter, punchier ones.

There still aren't many women nominated in the IBMA's six instrumentalist categories. Besides Hull, there's Missy Raines, who's pretty much dominated among bassists and currently leads her own adventurous band, The New Hip, and banjo player Kristin Scott Benson, a member of The Grascals who's won once before.

In a show of solidarity, most of these women—and some 46 others—sang or played on Bluegrass Bouquet, the latest of three Daughters of Bluegrass albums spearheaded by Dixie Hall. A track titled "Proud to Be a Daughter of Bluegrass"—a sort of scrapbook-style group version of "All American Bluegrass Girl," featuring the real-life daughters of Jimmy Martin and Carter Stanley—is up for IBMA Recorded Event of the Year. As big as the album's lineup is, it's nowhere near exhaustive. Nowadays, you need look no further than World of Bluegrass showcases and Fan Fest to find other quite good musicians who also happen to be women—like singer, songwriter, banjo player and former Porter Wagoner duet partner Pam Gadd, Amanda Smith (of the Kenny & Amanda Smith Band) and the young sister trio, Gold Heart.

"When I used to play festivals in the '70s, it was very routine for people to say, 'You play really good for a girl,' " says Brown. "And they weren't saying it as an insult.... It was just because there were so few women that that was just what they said. I don't think people say that anymore.... I think women are making the most interesting and cutting-edge and accessible music in bluegrass right now. So the female voice in bluegrass is loud and clear at the moment. Now, it would be really kind of backward for someone to make a comment like that. But back then, it was just their way of expressing their surprise at seeing a girl do something that usually was only done by boys."

Email music@nashvillescene.com.