[1] His father was a picture frame dealer who owned a small store on the Lower East Side.
[3] He was influenced by Francis Delafield while attending Columbia and by Edward G. Janeway when he first joined Mount Sinai.
He also came to know pediatricians Abraham Jacobi and Henry Koplik at Mount Sinai and initially considered working in pediatrics.
[8] Libman applied the research methods he learned abroad to study the bacteriology of the blood and perform autopsies to determine the cause of death.
He was also known for his diagnostic skills, claiming to be able to diagnose patients with his sense of smell and predicting diseases strangers had by their appearance.
He was a founding member of the American Society for Clinical Investigations in 1908, and in 1931 he established the New York Academy of Medicine's "Graduate Fortnight" to encourage people to share their work.
He helped establish a number of fellowships for medical research and education, including one at the Tuskegee University in Alabama, and during World War II he established the Henry Dazian Foundation for Medical Research to help Latin American doctors come to America.