Henry M. Pachter was born Heinz Maximilian Paechter on January 22, 1907 in Berlin, Germany. With the exception of a year at the University of Freiburg im Breisgau, Pachter received his formal education in Berlin and graduated from the University of Berlin in 1930, with a degree in history.

During his early years, Pachter became involved in the German youth movement and was a member of Der schwarze Haufen, but his socialist leanings soon led him to become disenchanted with the elitist nature of the group. By December of 1933, his association with socialist youth groups as well as publications in an underground leftist weekly, forced him to emigrate to the safety of Paris, where he remained for the next seven years. His future wife, Hedwig Rösler, whom he had met in 1928 in Berlin, joined Pachter in Paris in 1936. In France, Pachter became as a member of the Universitaire Populaire, often wrote under the pseudonym of Henri Rabasseire (Espagne Creuset Politique, 1938), and continued his association with both French and Spanish socialists. In September 1939, Pachter was interned in France, and began efforts to immigrate to the United States. Finally, having married Hedwig in 1940, they fled over the Pyrenees into Spain and eventually sailed from Portugal, arriving together in New York in April 1941.

Pachter quickly set about mastering the English language. During the early years in the United States Pachter worked as a consultant for both the Office of War Information (OWI) and the Office of Strategic Services (OSS), while still publishing articles in German as a U.S. correspondent for German newspapers and magazines, including the Deutsche Zeitung, Der Monat and Die Weltwoche. In 1945, he became editor of Economic Trends, where he continued until 1950.

In 1952, Pachter joined the History Department of the New School for Social Research as a lecturer, rose to professor and eventually chairman of the department. Pachter remained at the New School until 1967, and even served from 1963-1964 as acting director. In later years, Pachter also taught courses at Columbia University, the City College of the City University of New York and at Rutgers University in New Jersey.

Over the years, Pachter published hundreds of essays, as well as several full-length works on a broad range of subjects in history, economics and the social sciences. His main interest, as a proclaimed liberal social democrat and an avid anti-communist, was in explaining the meaning of socialism, in defense of the morality of socialism.

Henry Pachter died in New York on December 10, 1980.