Ernst Maximilian Posner (9 August 1892 – 18 April 1980) was a Prussian state archivist who fled to the United States during World War II where he served as the history department chairman, dean of the graduate school, and director of the School of Social Science and Public Affairs at American University.

[1][2][3] Posner was born on August 9, 1892, in Berlin to a wealthy Prussian Lutheran family of both Jewish and Christian heritage.

His uncle, Max Posner, who died ten years before Ernst was born, was an archivist with the Prussian Privy State Archives.

Having previously served in the military during peace-time, he rejoined Imperial German Army during World War I on both the Eastern and Western fronts.

At the Archive he helped alter the arrangement and description for all government records that were newly retired.

With the help of friends, Eugene Andersons of American University in Washington, Waldo Gifford Leland of the American Council of Learned Societies, Solon J. Buck of the National Archives, Posner began to position himself within the world of archives in America.

[1] Posner then traveled to Harvard, Yale,[5] the Rockefeller Foundation, and the Oberlander Trust looking for any type of employment.

[6] Still needing a visa, the Posners ended up in Sweden for four months where he was able to present a lecture entitled "Archival Administration in the United States."

Posner, carrying on the dream of Solon J. Buck, began to establish a program for archivists in the United States.

[7] For a period of two years, beginning in 1939, Posner and Buck taught a class entitled "The History and Administration of Archives."

For example, Posner was accused by Senator Kenneth McKellar for attempting to make the bombing of the National Archive easier by switching the records boxes from steel into cardboard.

[12] Posner took great pride in one of the courses that he offered during summers entitled "The Institute on the Preservation and Administration of Archives".

According to his own words, "[i]t became the prototype of many such courses now being offered in various parts of the country and has helped to create some esprit de corps and to impart professional know how to those working in the archives field.

"[13] At that time, Posner's research showed that twelve states did not have any official archivists and that nine of those had no formalized system for the management of permanent government records.