Among three children, his son, Mark Jennings, is currently director of Choral Activities at Truman State University in Kirksville, Missouri.
A former student and colleague of Olaf Christiansen, Jennings understood and respected the choir's distinct Lutheran tradition in his programming.
Jennings prepared the choir to record Ravel's Daphnis et Chloé with the Minnesota Orchestra under the direction of Stanisław Skrowaczewski, and during his tenure, he arranged for several notable conductors to rehearse and lead the St. Olaf Choir in concert, including Polish composer Krzysztof Penderecki, Bach specialist Helmuth Rilling, British organist Simon Preston, and Robert Shaw.
After his retirement from St. Olaf in 1990, he served as a visiting professor and choral conductor at Gustavus Adolphus College and the University of Arizona in Tucson.
His writing is marked by the elegant and efficient part-writing, voluptuous harmonies and great attention to the meaning of the text.