Cohen was born in Milwaukee, Wisconsin, to Bessie ("née" Rubenstein) and Aaron Cohen. He was known to by several nicknames. He was once dubbed "The Man Who Built Medicare" and John F. Kennedy tagged him "Mr. Social Security", although it was Frances Perkins, the first woman Secretary of Labor (under FDR), who was the architect of social security. "The New York Times" called him "one of the country's foremost technicians in public welfare." "Time" portrayed him as a man of "boundless energy, infectious enthusiasm, and a drive for action." He was a leading expert on Social Security and a member of Americans for Democratic Action.