McElroy, who later became a staff photographer for Newsweek, captured the works of a number of prominent artists of the period, including Allan Kaprow, Jim Dine and Claes Oldenburg.
Getty officials said the acquisition was partly a donation by McElroy's widow, Evelyn McElroy, and partly a purchase. The acquisition includes approximately 700 vintage prints developed by McElroy, 10,000 negatives and contact sheets, and a paper archive that includes posters and correspondence.
McElroy is perhaps best known for photographing so-called happenings, a type of performance art that combined live performance and abstract expressionism in a new physical form.
The Chicago native was born in 1928 and served in the Army. He later attended
He died in 2012 at the age of 84. The Getty said that McElroy's photographs captured a key period in modern art.
"This acquisition will greatly expand access to his work and enrich our understanding of this pivotal moment in art history," said Thomas Gaehtgens, director of the Getty Research Institute, in a prepared statement.