He is noted for his books, Thespis: Ritual, Myth, and Drama in the Ancient Near East (1950), The Dead Sea Scriptures, about the Dead Sea Scrolls, as well as his one-volume abridgement of Sir James Frazer's massive 13-volume work The Golden Bough, to which Gaster contributed updates, corrections and extensive annotations.
He was also a leading Zionist, and named his son after his friend, Theodor Herzl, who had died in 1904, shortly before the boy's birth.
His master's thesis, a preview of his key work, was titled "The Ras Shamra Texts and the Origins of Drama."
Gaster's first full-time American post came in 1945, when he served for a year and a half as chief of the Hebraic Section of the Library of Congress in Washington, D.C.
Most of the books for which Gaster is best known were published in the 1950s, including his translation of the Dead Sea Scrolls, widely admired for its felicitousness; Thespis, his application of the Frazerian myth-and-ritual theory to the ancient Near East and beyond; and his abridgment and updating of Frazer's The Golden Bough (The New Golden Bough [1959]), in which he retained the theory but updated the data.
[2] Only in 1966, at the age of sixty, did Gaster secure a permanent full-time academic post, as professor of religion at Barnard College, the women's undergraduate division of Columbia University.