Freed's formal music education was at the University of Pennsylvania, where he earned a bachelor's degree at the age of 18.
After graduation from Penn, Freed briefly held a teaching post at The Curtis Institute of Music.
He also studied piano with Józef Hofmann and George Bayle, and organ with Rollo Maitland.
Freed returned to the United States in 1934, and shortly after he was employed by the composition department at Temple University from the mid-1930s until the mid-1940s, but sources disagree as to the dates of his appointment.
In 1951 he was also hired as Harmony instructor at the Hebrew Union College, School of Sacred Music.
He also served as a radio commentator for performances of the Philadelphia Orchestra, and edited a number of scores in conjunction with Lazare Saminsky.
Freed's primary contribution to scholarly discourse is his book, Harmonizing the Jewish Modes, a theoretical treatise discussing Jewish sacred music in the context of Western European music theory, particularly the synagogue mode and its lack of a strong tonic-dominant relationship.
Freed was also active as a synagogue musician, acting as organist and choirmaster at Temple Keneseth Israel in Philadelphia.
New York: Sacred Music Press of the Hebrew Union College, Jewish Institute of Religion, 1958.
A Jewish Composer by Choice: Isadore Freed, His Life and Work : A Program Handbook.