California-born soprano Mary Ellen Callahan appears frequently as soloist in a variety of repertoires. In a recent performance of Carmina Burana at the Metropolitan Opera house with American Ballet Theatre, the New York Times said she was “first-rate”. She performed Mahler's 8th Symphony with the Utah Symphony and conductor Keith Lockhart and was called “stunning” by the Salt Lake Tribune. In a performance of the Mozart Great Mass in C Minor, the Washington Post hailed her as “radiant and wondrously agile”. She has been invited to sing the Messiah by conductor Richard Westerfield with the Alabama Symphony Orchestra, the Buffalo Philharmonic, and the Harrisburg Symphony. She sang performances of Mozart's Great Mass in C Minor with the New Mexico Symphony Orchestra where critics said “she radiated a purity and warmth which pierced the heart”, and was invited to return to the NMSO to sing Mozart concert arias and Requiem, as well as the Handel Messiah in subsequent seasons.

She is a frequent soloist with the American Bach Soloists in San Francisco, and has performed a program of Bach cantatas and the B Minor Mass with them. In a performance of Handel's Messiah with the San Antonio Symphony, she was praised for her “liquid silver fluency”. Collaborating repeatedly with the Washington Bach Consort, she has been a soloist in Bach's Missae Breves and B Minor Mass, the CPE Bach Magnificat and many cantatas, and she was also engaged by that group for their tour of Germany. She has performed Bach's B minor Mass in Washington DC's Kennedy Center with Norman Scribner and Bach’s St. John Passion in New York’s Lincoln Center with Kent Tritle.

In Carnegie Hall, she has performed the Bach Christmas Oratorio, Mahler's Eighth Symphony, Handel's Messiah and a solo recital in Weill Hall to a sold-out house. She recently sang the Bach Christmas Oratorio with the St. Luke's Chamber Ensemble. She was a soloist in several performances of Mahler's Eighth Symphony with the Hartford Symphony and previously with conductor Bill McGlaughlin in his farewell performance with the Kansas City Symphony. In New York City's Town Hall she has sung Handel's Alexander's Feast with the Dessoff Choirs. Ms. Callahan sang Bach's Wedding Cantata in an enthusiastically received performance with Musica Sacra conducted by Richard Westenburg. Familiar to New York City audiences as soloist with the Collegiate Chorale, the Riverside Choral Society, the Dessoff Choirs and the Central City Chorus, she has performed works including Mahler's Second Symphony, Brahms' Ein Deutsches Requiem, the Fauré Requiem, Handel's Judas Maccabeus, the Haydn Lord Nelson Mass and Mass in Time of War, Mozart's Solemn Vespers, Purcell's Dioclesian, the Poulenc Gloria, and Schubert's Mass in G.

Ms. Callahan won first prize in the Musica Sacra Bach Competition and third prize in the New York Oratorio Society Competition. She has won fellowships to both the Stonybrook Bach Aria Festival and the Carmel Bach Festival. Invited to return to the Carmel Bach Festival as soloist in subsequent seasons, she received reviews which spoke of her "exceptionally pure tone" and "compellingly lovely voice".

Ms. Callahan's recently recorded Gluck's operas La Corona and Il Parnaso Confuso with the Queen's Chamber Band for Albany Records. She can also be heard in the world premiere recording of Handel's opera Faramondo, a Vox Classics CD. With the Washington Bach Consort and conductor J. Reilly Lewis she has recorded the J.S. and C.P.E. Bach Magnificats, available from Newport Classics, as well as The Bach Masses, available on Loft Recordings.  She is featured on a Helicon Classics CD called A European Christmas, and she is the guest soloist with the Russian Chamber Chorus of New York in a CD of contemporary Russian music by Yuri Yukechev entitled My Heart Is Ready, released by Helicon Classics. Ms. Callahan also sings songs by Amy Beach on the Newport classics CD entitled Distant Playing Fields.