Edgar J. Kaufmann was born on November 1, 1885 in Pittsburgh, Pennsylvania. He attended the Shady Side Academy and later spent a year studying at Yale University before embarking on an apprenticeship program in retail. In 1909 he married his first cousin, Liliane Kaufmann. That year he discovered Bear Run, which would become the site of their famed residence Fallingwater designed by Frank Lloyd Wright.

Kaufmann took charge of his family's department store in 1910, the same year that his son, Edgar Junior, was born. He quickly established himself as a formidable businessman, and Kaufmann's grew to become the most prominent Pittsburgh department store of the 20th Century. During this time, Kaufmann began renting the Bear Run property as a camp for his employees, and purchased it on July 28, 1933 under his wife's name.

1934 marked the beginning of Edgar J. Kaufmann's relationship with Frank Lloyd Wright. Kaufmann was active in spearheading New Deal public works initiatives in Pittsburgh, and commissioned Wright for several projects. That year, Edgar Junior went to apprentice with Wright at his workshop, Taliesin, followed by Edgar and Liliane. On December 18, 1934, Kaufmann commissioned Wright to build his residence, Fallingwater, at Bear Run.

Fallingwater was designed in 1935, the initial sketches drawn up in a matter of hours pending the Kaufmanns' imminent arrival at Taliesin on September 22, Wright having assured them that the plans were ready. In October Wright presented the family with the intricate colored pencil drawings that have been repeatedly invoked in the scholarship on Fallingwater.

The Bear Run property was not without fault, however. Correspondence between Kaufmann and Morris Knowles Engineers in April 1936 delineates several concerns regarding the foundation upon which Fallingwater was to be built: "…we cannot recommend the site as suitable, from a structural standpoint, for a building of importance such as that contemplated." Ignoring this warning, construction began on Fallingwater in June.

In November 1937, Fallingwater was complete, and Frank Lloyd Wright had reclaimed a level of notoriety that he had not enjoyed in over a decade. Along with his public profile rose Wright's ego; he remarked to Kaufmann in a letter dated October 25, 1937, "…you got your money's worth out of an architect if ever a man did and probably for the first time in your life?"

Before Fallingwater was inhabited by the Kaufmanns in December 1937, though, issues with the home began to arise. Allegedly a result of extreme humidity, the interior woodwork began to warp. "We really are not surprised to learn that some of the doors are warped, as Mr. Tafel told our Mr. Cooper recently that the interior of Mr. Kaufman's house was very wet and that as a matter of fact, the water was running off some of the walls," the president of Gillen Woodwork Corp. stated in a letter on November 24. The Kaufmanns, scandalized, refuted this contention, blaming Gillen for the flawed doors, and indignantly informing Taliesin apprentice Edgar Tafel of the claims being made in his name: "I am enclosing copies of correspondence since your name occurs in it and simply wish you to be up-to-date on the rumors that are going around." (December 1, 1937)

In 1938 Fallingwater received extensive praise and criticism, inspiring numerous articles and earning Wright the cover of Time magazine. By the early 1950's, however, Fallingwater's detractors were vindicated, as the foundation began to sink. "It may not seem much but it is very noticeable when one looks at the house," Kaufmann wrote in May 1951.

This period was also marred by instability between Kaufmann and Wright. Correspondence reveals the deterioration of their relationship, as egos and tensions regarding other projects, such as the un-built Point Park, prevailed. "Dear EJ: You are cheating. Cheating me, yes – but most of all cheating yourself … Suppose you had done the same with… Fallingwater. Would you ever have built it? Certainly not…" (December 29, 1949). To Edgar Junior, Wright wrote, "Father seems to be with architects as he is with women. There is no chance for me now. I haven't the patience to "trail along." (January 25, 1950)

A month later, Wright's paranoia regarding Kaufmann's consultations with other architects reached its apex: "I realize that we will never build any thing more together which is a genuine sorrow to me for I conceived a love for you quite beyond the ordinary relationship of client and Architect. That love gave you Fallingwater... And, E.J. I hope I can at least save you from the funny wilted-prick you would erect … a form of phallic-worship distressing in the extreme with the vulva lying so helpless beneath the poor emblem. I would save you from that caricature as a last service. But probably you have seen it for yourself, by now, anyway." (February 25, 1950)

1950 also saw discord in the Kaufmanns' marriage, alluded to by Wright in the correspondence: "Dear Edgar: You have never seemed dearer to us than in this surprise-present you – with Liliane – so generously sent to our work… Is the implication that you and Liliane are reconciled and no violent break-up ahead?" (December 11, 1950). In 1951, Mrs. Kaufmann lamented in a letter to Wright, "…I must leave Fallingwater which is a great sorrow to me." The Kaufmanns never divorced, however, and Liliane died in 1952.

In the final years of Kaufmann's life, his friendship with Frank Lloyd Wright remained tumultuous. "My dearest of all Edgars: You are not quite right in the head (or the heart) where this "Pittsburgh-Glass" matters," Wright wrote in the early 1950's, referring to a dispute regarding payment for materials used in an exhibition of the architect's work at the Guggenheim Museum. "Commerce got the better of Beneficence," Wright sniped in 1953. Finally, in 1954, he offered an olive branch: "Well, I've missed you. In spite of your curious reversion to type now and then, I love you and have reason to do so. In the past? When do we meet and blow away the bad odors, etc., etc."

In 1955, further concerns arose regarding Fallingwater's structural stability. "…we believe that for some years this structure has been quietly asking for help… and that in the near future it will demand assistance in a more forceful manner," wrote engineers Hunting, Larsen & Dunnells. Kaufmann died on April 15 that year, and Fallingwater flooded in August 1956. In the years following his father's death, Edgar Junior assumed responsibility for the home, donating it to the Western Pennsylvania Conservancy in 1963, some time after Wright's death in 1959. The Conservancy continues to maintain Fallingwater as a museum, and the legacy of the Kaufmann family's singular relationship with Frank Lloyd Wright endures.