Roustabout! will make its 2007 debut tonight when Washington, D.C.'s atmospheric rock band Cedars and Pittsburgh's rock trio Chalk Outline Party come to the Darkhorse Tavern, 128 E. College Ave.

Both bands dealt with recent lineup changes, with Cedars going from a five-piece to a quartet and Chalk Outline Party downsizing to its current three-piece lineup. Likewise, both bands have been forced to alter their styles accordingly.

Cedars, with its first Roust appearance, has tried to replace its lost band member by maintaining its music-by-committee approach to making sonic atmospheres, Francisco Lazzaro (bass) said.

"We definitely have a soft side for stuff that's atmospheric and moody, but we also have other stuff that we've recorded that's up-tempo," Lazzaro said.

Chalk Outline Party, on the other hand, has had to account for some instrument trading. The band's lead vocalist Aaron Jentzen was forced to learn to play bass, and now drummer Jeremy Papay plays both drums and keyboards at once.

"It ended up changing our sound a lot," Jentzen said. "Some of our older stuff was more progressive-sounding. We kept a few songs that we liked; a lot of songs we got tired of anyway. We adapted some songs and we also wrote a thousand more songs that are better."

Jentzen said despite the adjustments, the band has been able to move forward.

"You have one less cook in the kitchen, and it can make things a little easier," he said. "It's been a really nice fit. For me, I was a little nervous playing bass, because I'd never done that before. My band members thought it'd be a good idea, and I went and bought a bass the next day."

For Cedars, the change has been more than a stylistic one. Lazzaro said the band was originally named Cartel until the Atlanta pop-punkers gained popularity and usurped that title. But he said the band began a new direction as Cedars.

"We do have the trademark of the name, and we kind of contacted the other Cartel and said we have this registered," Lazzaro said. "We weren't willing to fight over the name. There's no use in paying a couple grand for a name when you can use that money to buy a van or for recording. We changed the name and that was the new beginning. I think it's worked out for the best. We're enjoying the music more that we're doing now."