One of the more visible rewards of America's concern with cultural roots has been the re-awakening of interest in Irish and Irish-American music over the past five years. Washington has long been in the forefront of that movement; there are a dozen pubs offering the music, as well as a score of concerts a year featuring the best performers from across the waters. And now from County Montgomery in Maryland comes the vital and engrossing resonance of Celtic Thunder, whose self-titled album (Green Linnet SIE-1029) has the grace of a newly-discovered poem by Yeats and the warmth of a midnight idyll by O'Casey.

The five musicians of Celtic Thunder bring together not only a variety of experience and a deep store of material, but a respect for traditions studied first-hand. Robert Burns' elegaic poem, "The Deadly Wars," which they learned in Scotland as an a capella solo, is transformed here into a melancholy meditation on war, pulled along by Nita Conley's mournful voice into almost accidental group harmonies that are as grand as they are chilling. Two cuts later, Jesse Winch's zestful reading of "Bold Thady Quinn" enlivens a light and boastful Irish music-hall song which Linda and Steve Hickman underscore with bright whistle and harmonica fills. On "The Gem of the Roe," Conley again expresses her lyrics like a warm breeze, with the other voices entering on the chorus.

The group's experience as a ceili (dance) band comes out in six sets of polkas, jigs, slides and reels, the last a truly demanding genre. One set of slides was composed by Terry Winch and dedicated to the large circle of friends and family he wrote about so eloquently in his book of poetry, "Irish Musicians." The exuberant graces of the instrument -- accordion, flute, guitar, fiddle, tenor banjo and bodhran -- pull at each other with a pomp of circumstances that speaks worlds of the intimacy of shared music.

Celtic Thunder is at once earthy and ethereal, obedient to what Yeats called "some hidden magical breath." Nowhere is this more evident than on Terry Winch's gorgeous and eloquent "The Best Years of Our Lives." If the song has an air of familiarity, it's because it's often been used before in both Irish and British folk traditions, built around one of those haunting melodies handed down through generations. Winch uses it with a poet's zeal to encapsulate the 75 years of agonizing separations and cathartic reunions that define his family's history. It's a monumental theme handled with simple grace, clouds of difficult memories clearing away to reveal a family intact, triumphant and proud. That's the story of the music on "Celtic Thunder" as well.

Trapezoid, a West Virginia band that often plays in the area, also works from a traditional base, but with a different emphasis. The group's third album, "Now and Then" (Flying Fish FF239) is far removed from their earlier efforts, which were dominated by hammered dulcimer. Lorraine Duisit's soprano and Freyda Epstein's alto intertwine in sensuous duets; alone, each voice curls around the lyrics, warming them, breathing belief into every word. Trapezoid is exploring a chamber/folk mode reminiscent of Pentangle, but less percussive and more deeply grounded in American roots and branches.

On ballads like "Do You Love an Apple" and the classic "Lakes of Ponchartrain," the influence of folk-revival groups like Planxty and DeDanaan is evident. On "Devrah's Delight" and "The Silverplume Waltz," the four members' classical training is echoed in bright folk melodies that sound like what Mozark might have written had he visited the colonies. The blend of guitar, cello, violin, viola, mandola, bowed psaltery and bass throughout "Now and Then" creates an eloquent and pastoral serenity.

Lest this sound stiff, Trapezoid bounces around with an electric repertoire that encompasses American fiddle tunes, the Louis Jordan jump blues "Ain't Nobody Here But Us Chickens," some swing string tunes in a Dan Hicks vein, Irish and English folk songs and a moonshiner's ballad. Duisit, a promising composer with a rare ability to extend traditions through her own work, is also a startling singer; her unhurried duet with Epstein on "Ponchartrain" is exquisite. Epstein herself shines on "Apple," sad and sultry.

Paul Reisler and Ralph Gordon join Duisit and Epstein on the chorus of some songs, but the two women shoulder the weight of the singing. Blessed with expressive arrangements and a collective sense of wonder, Trapezoid has constructed a beautiful record. Celtic Thunder makes toe-tapping music that inspires the heart; Trapezoid reaches the same destination along a more cerebral path.