The group, currently a six-piece ensemble with founders Joey Burns and John Convertino as the only constant members, will have representatives of several humanitarian groups, including Humane Borders and Music For America, on hand during its December shows to speak with interested concert-goers about border and immigration issues.

The group is running a contest at its website for fans looking to help the band spread the word on issues of concern. Winners will receive free tickets and CDs, among other prizes.

Still backing this year's "Garden Ruin" release, tCalexico kicks off a seven-date tour Dec. 2 in Tucson, AZ, with back-to-back opening slots beginning Dec. 8 in San Francisco supporting Los Lobos.

"An inspiration for many years, Los Lobos have more variety and depth than many American bands," Burns said in a press release. "Their musical tradition stretches across different styles of music, and yet they still carve out their own voice."

Calexico will follow up with a long stretch of tour dates with Iron & Wine [ tickets ] in January, when the twin contingent set off for a trek across Japan. The full itinerary is listed at the band's website.

"Garden Ruin," Calexico's fifth studio release, was recorded in the group's hometown of Tucson, AZ, with producer JD Foster (Marc Ribot, Richmond Fontaine) behind the boards. The core duo of Burns and Convertino, who tended to dominate Calexico's earlier studio recordings, sought more input from their touring lineup on "Garden Ruin," according to the band's online bio.

"This album was a conscious decision to try something new and tap into strains in our musical fabric that haven't been highlighted in the past," Burns said in a message posted at the band's website. "Touring with bands like Wilco and Iron & Wine had some influence, but everyone was trying new instruments or techniques."

Calexico, whose previous album was 2003's "Feast of Wire," toured extensively with Iron & Wine's Sam Beam earlier this year and in late 2005, a collaboration which also produced this year's "In the Reigns" EP, featuring music both groups recorded together in 2004.