Morton Lauridsen (b. 1943) is an American composer of principally choral music.  He is best known for his six vocal cycles and his setting of O Magnum Mysterium.  He is a 3-time Grammy nominee and the recipient of numerous awards, including the National Medal of Arts, presented to him by President George W. Bush in 2007.  He was composer in residence for the Los Angeles Masters Chorale (which premiered O Magnum Mysterium) from 1994-2001.  He has been a professor of composition at USC-Thornton, where is currently Distinguished Professor of Composition, for more than three decades.

O Magnum Mysterium has been received thousands of performances and at least 100 professional recordings since its 1994 premiere, making it one of the most performed compositions of the last 20 years in its original setting.  The wind band arrangement by H. Robert Reynolds, retired director of the University of Michigan Bands, can claim similar accolades within wind band circles.  Of his original version, Lauridsen writes:

For centuries, composers have been inspired by the beautiful O Magnum Mysterium text with its depiction of the birth of the new-born King amongst the lowly animals and shepherds.  This affirmation of God’s grace to the meek and the adoration of the Blessed Virgin are celebrated in my setting through a quiet song of profound inner joy.

O Magnum Mysterium is perhaps best understood in its original choral setting.  So here is one hell of a performance of it:

And the band version (written a half-step higher):

Morten Lauridsen on Wikipedia.

Morten Lauridsen’s personal website.  For a program note on O Magnum Mysterium, click “Publications”->”View by Ensemble”->”O Magnum Mysterium”

An extensive 1999 interview of Lauridsen conducted by Bruce Duffie.  It was published after the 2007 National Medal of Arts ceremony.