Born in Ellenville, New York, to Orthodox Jewish immigrants from Ukraine and Lithuania, Leventhal was eight weeks old when his father, Samuel, died in the 1918 influenza pandemic at the age of 34.
They then moved to the Bronx, where in 1935, at James Monroe high school, Leventhal, already a member of the Young Communist League, was arrested for organizing an "Oxford Pledge" strike, aimed at persuading students to refuse to fight further wars.
He later founded American Friends of India, and, at a 1954 party hosted by the Indian delegation to the United Nations, Leventhal met Nathalie Buxbaum, a UN guide, who was to become his wife.
But Leventhal's commitment to the group and their audience persisted, and in 1955 he organized a Christmas Eve Weavers reunion concert at New York City's Carnegie Hall, persuading the members to take part by convincing each one that the others had already agreed.
Denied a passport until 1955 because of his Communist sympathies, Leventhal organized world tours for folk singers that the U.S. State Department forbade from taking part in official cultural exchanges.
Leventhal's tastes were eclectic, from Lightnin' Hopkins' blues to jazz greats such as Duke Ellington and Dexter Gordon to folk traditionalists Cisco Houston, Theodore Bikel, Oscar Brand and Mahalia Jackson.
He represented Ireland's Clancy Brothers, Britain's Ewan MacColl, Donovan and Pentangle, and also had an eclectic international roster including Jacques Brel, Nana Mouskouri, Mercedes Sosa and Ravi Shankar.
[3] After Guthrie's death in 1967, Leventhal virtually adopted Woody's son Arlo, who worked in his office before making his hit record "Alice's Restaurant".
Leventhal may have been defined best in the program notes for that concert, as embodying the definition of the Yiddish word, mensch, meaning "man" in the sense of "an upright, honorable, decent person, someone of noble character".