Sims Delaney-Potthoff, Harmonious Wail's founder, leader and mandolinist , credits Jethro Burns with the band's unique, enticing style of mandolin-driven gypsy-jazz. Sims studied for seven years with Burns, the legendary jazz mandolinist, laying the foundation for Harmonious Wail's acoustic string sound. He furthered his studies with Matt Glaser at Boston's Berklee College of Music, honing his skills while immersing himself in the "gypsy" music of Django Reinhardt and Stephane Grappelli (Lester Young, Charlie Parker, Bireli Lagrene, Duane Allman, David Grisman, and Louis Armstrong are also on his list of musical heroes). Sims also plays a 1937 Gibson Tenor Guitar (tuned as an octave mandolin), sings, writes and arranges for the Wail. He founded the group in 1987.

Vocalist Maggie Delaney-Potthoff is a captivating performer. Equally at home scatting over a bebop tune, soaring on a solo, or blending with the Wail's tight vocal harmonies, she delivers both powerhouse tunes and ballads with confidence and ease. Her sensual, sinuous movements (a product of her background in dance and theatre) and her use of a cardboard box played with brushes as a drum add to the charm she exudes onstage.

Guitarist and vocalist Tom Waselchuk jumped at the offer to join Harmonious Wail in 2001, completing a career cycle that began in partnership with Sims Delaney-Potthoff. Tom and Sims performed together from 1979 through 1983 in the Stone Oak Bluegrass Band before parting to pursue individual goals. In the ensuing years Tom performed with and led jazz groups (Full Count Jazz Band, Wholly Cats), played folk and blues (Katzenjammers, The Rubato Brothers), western swing and honky tonk (The Dang-Its, Cris Plata & Extra Hot), and even wrote for and performed in musical theatre productions. But jazz is the thread that has tied his career together.

Matt Rodgers'powerful, passionate and energetic bass playing lays the foundation for the Wail’s groove.  The Wisconsin native, who cites Miles Davis, Ray Brown, Ron Carter, Christian McBride, Charlie Haden, Sting, and James Jamerson as musical influences, studied jazz and bass studies at UW-Madison with bass maestro Richard Davis.  He has played, toured, and/or recorded with, among others: Lucas Cates, Mark Croft, and Kikeh Mato.