Tegan & Sara's latest album, "Sainthood," has opened the door for the two to spend more time writing together.

Though the twin sisters have composed apart from each other during their 12 years as a group, they held a writing session together before hitting the studio for "Sainthood," and one of their songs, "Paperback Head," made the cut. "We wrote a bunch of other stuff together as well," Tegan Quinn tells Billboard.com. "It was pretty late in the process where we'd sort of determined what songs we wanted to record already. We didn't feel we wrote anything else that challenged those songs."

Tegan says that the duo found their writing styles were not particularly compatible, with Sara by far the more "meticulous" of the two. But with "Paperback Head" the sisters, who live on opposite sides of their native Canada, discovered they could work together if they weren't in the same room. "We've been sharing files and sending MP3s back and forth and collaborating that way," she says. "We find it easier. "But I'm glad we did try to sit in a room together and do it so we could see how we each worked. I felt proud we were able to do it without being arrested or killing each other."

Tegan, who also did some writing for "Sainthood" with AFI bassist Hunter Burgan, her partner in a forthcoming side project, predicts that "there is definitely a project in the future that will just be Tegan & Sara collaborating on songs. I know a lot of people are like, 'OK, whatever;' they assumed this whole time we'd been writing together. But I think a record written solely as Tegan & Sara songs would sound very different than anything we've done before."

That project will certainly have to wait until after Tegan & Sara tour in support of "Sainthood." The duo is on the road in North America through early April, with Australian dates on tape for May. They'll also be part of this year's Honda Civic Tour, but they're particularly excited about being on Sarah McLachlan's Lilith Fair bill when the festival tour resumes this summer.

"The year we started playing music professionally was the year Lilith Fair ended (1999)," recalls Tegan. "We did a Lilith Fair date that year on the Village Stage, the local promoter's stage. So for 10 years we've been answering questions about playing Lilith Fair and we really...didn't. So we can't wait. I think Lilith Fair is a one of a kind festival, and it's been missed the last 10 years -- at least by artists like us."