Initially he was interested in pursuing a career in sports journalism, but after attending classes in advertising and public relations he decided that was where his future lay.

[3] After basic training, he was posted to Fort Eustis, Virginia for a few months, then army headquarters at Orléans, France as an information and education specialist,[5] who lectured to the troops.

For a short while he worked for a show business publicist where his main clients included Milton Berle, who helped start television in the United States, Tony Bennett and Pearl Bailey.

[3] Credited as "the father of public relations",[8] Leaf went on to create a global network of offices which helped Burson-Marsteller become the world's biggest PR firm during his tenure.

[7] After giving a speech in Moscow, B-M was hired by Vneshtorgreklama, the Russian state advertising agency during the Cold War, and helped set up the first PR firm in the Soviet Union.

[3][5] He launched the first international PR firm in the Middle East and started Burson-Marsteller offices throughout Europe, Asia, South America and Australia.