Ernst Cohn authored a number of books during his philatelic career, including: Die “Papillons” von Metz (1976), The Flight of the “Ville d’Orleans (1978), Ordinary Mail by Diplomatic Means (1995), Unusual Mail in Occupied France 1870–1871 (2000), and A Book of Postal History (1988) which contained many of his articles he had previously written for The American Philatelist.
At the American Philatelic Society, he served a number of posts, including representative to the FIP Postal History Commission and on the Postal History Committee.
At the Postal History Society he held a number of posts including president and associate editor.
He received recognition for his work from the American Philatelic Congress, the Fédération Internationale des Sociétés Aérophilatéliques (FISA), the Fédération Internationale de Philatélie (FIP), and others.
He was named to the American Philatelic Society Hall of Fame in 2006.