By the age of six, Jenkins had already begun piano lessons;[3] soon afterward, he started composing small pieces in elementary school.

At the same time, he studied composition and counterpoint with Vincent Persichetti at the Philadelphia Conservatory (which became part of the University of the Arts in 1962).

During his military service, Jenkins was the arranger for The United States Army Field Band as well as for the Armed Forces Radio Network.

[13] Jenkins began his position as a tenured Professor of Theory and Composition at the Mary Pappert School of Music, Duquesne University in 1961.

At Duquesne, he taught music theory, orchestration and composition and "was beloved by his students, colleagues and fellow musicians.

"[3] During his term at Duquesne, Jenkins served as Head of the Theory and Composition Department in the university's School of Music.

[14] Much of his collected choral works are available as part of Gumberg Library's Music Library Resources, alongside those of jazz guitarist and educator Joe "Handyman" Negri, another music educator who also influenced youth (in Mister Rogers' Neighborhood) and mature minds as a professor at Duquesne.