Mention Irish Fest’s 30th anniversary and a number of images come to mind: patrons eating corned beef (10,000 pounds in 2009, to be exact), plenty of pub beverages, bagpipers, lectures on Irish history and culture, children’s contests for red hair and freckles, leprechauns (yes, there’s a gathering of the little men in green for the kids) and plenty of promotions to make the Fest affordable in these recessionary times.

And that doesn’t even cover the Irish music, which includes a Harp Tent featuring harpists from around the world playing the musical instrument that symbolizes Ireland. Celtic music even has its own rhythm section featuring the bodhran frame drum. And there are fiddles, of course—lots of fiddles.

But what actually makes an Irish band, well, Irish?

“It doesn’t have anything to do with instrumentation,” says Michael Tierney of Milwaukee’s well-known Irish rock band Reilly. “It really has to do with the lyrical content and what’s considered musical tradition.” (Reilly will be playing Thursday and Friday at Irish Fest.)

When it comes to “musical tradition,” anything goes, as Reilly mashes it up instrumentally and otherwise. Tierney, who’s been with the group since 2003, sings and plays guitar in addition to the whistle and bouzouki—a Greek instrument like a mandolin but with a long neck.

“It’s something I got into watching other Irish musicians play. There’s so much cross-culturalization these days,” Tierney says, referring to global groups like Afro Celt Sound System, which mashes up West African and Celtic music against trip hop and techno beats.�

Reilly, which celebrates its 10th anniversary this year, is named after its founder, the late Brian Reilly. In addition to Tierney, the current lineup includes Joe Neumann on bass and vocals; Brian Bruendl on drums and vocals; Bruce Troeller, who’s been coaxed out of “semi-retirement,” on accordion, banjo, mandolin and vocals; and fiddler Kimmy Unger.

The Reilly musicians, who range in age from 35 to 40, all play in other bands, including a trio version of Reilly (listed as “Reilly Trio” at Irish Fest) featuring Tierney, Troeller and Unger. Tierney also plays in the Metallica tribute band Beatallica.�

What distinguishes Reilly from its musical brethren is band members putting their own spin on the Celtic traditions. “A lot of things we like to do are not ours,” Tierney says. “We try and work some of our flavor, Reilly’s interpretation, into the music.”

Case in point: The band will play Talking Heads’ “Burning Down the House” since it has a “basis in world music,” Tierney says. That goes for the regular requests as well, be they Metallica’s “Whiskey in the Jar,” “Dirty Old Town” by the Pogues or “Rocky Road to Dublin,” the 19th-century traveling tune covered by everyone from The Chieftains to the Dropkick Murphys.

The globalization of Irish Fest extends well beyond the music. Jane Anderson knows—now the Fest’s executive director, she’s been with the event from the start, beginning 30 years ago as an unpaid volunteer. Anderson, who has served as executive director since 1994, has watched the event grow from its early days as a music festival to a major cultural and entertainment event for people of all ages.

“We want it to be a family event,” she says. “We want the festival to appeal to the larger community.”

The community itself plays a large role. Irish Fest has approximately 4,000 volunteers over its four-day run to make it work, including 150 people who plan year-round, Anderson says. Irish Fest now features 16 stages, ranging from the traditional/contemporary Irish sounds of Reilly to performances representing other cultures.

As Tierney puts it, “A lot of the Irish stuff, like America, is a melting pot these days.”

Irish Fest runs Aug. 19-22 at Henry Maier Festival Park. For more information, visit www.irishfest.com.