Sugarland will sweeten the already star-studded line up at the 18th Annual Nobel Peace Prize Concert on Sunday, December 11 in Oslo, Norway. This year's line up includes David Gray, Jill Scott, Janelle Monáe, Matthew Morrison, Ellie Goulding, Bernhoft and the World Youth Choir.

Willie Nelson, Tim McGraw, Wynonna and Dierks Bentley are just a few of the country musicians that have joined an array of performers from pop, jazz and other formats for past concerts.

In a blog post on their website, Nettles and Bush called the invitation to perform an "incredible privilege" and noted how this year's Nobel honorees  -- Ellen Johnson Sirleaf, Leymah Gbowee and Tawakkul Karman -- worked for what the Norwegian Nobel Committee called “their non-violent struggle for the safety of women and for women’s rights to full participation in peace-building work."

As fans know, such work is near and dear to the hearts of Sugarland. For years, the duo has given $1 for every concert ticket they sell to the Shalom Foundation charity that aids the needy, especially children, with funds for health care and clean facilities.

Tickets for the Nobel Peace Prize concert are on sale now, and organizers again expect about 6,000 attendees. Can't spring for a ticket? The Olso Spektrum concert is broadcast to about 120 countries. To find out how to buy tickets or tune in, check the concert website.

Want to hear the duo live here in the U.S.? Sugarland are still on the final leg of the Incredible Machine tour and by all accounts the recent concerts have been "incredible." At the Orlando show on Thursday, Oct. 20, women in the audience wearing pink tutus and boas caught Nettles' eye. She asked if they were there for a bachelorette party or supporting breast cancer awareness. When the women said it was for the latter, Nettles said, "We love boobies! And we hate cancer!"

Calling that the quote of the tour, Nettles and Bush wrote "You're free to borrow that for bumper stickers, t-shirts, what have you. We think it pretty much sums things up!" Find out more about the Sugarland tour, including upcoming dates, on their website.