Phyllis Greenacre, American psychoanalyst and physician, was born May 3, 1894 in Chicago, Illinois, and died October 24, 1989 in Ossining, New York.

Greenacre was the fourth of seven children of Isaiah Thomas, a prominent lawyer, and Emma Russell. After graduating from Rush Medical College in Chicago, in 1916, she became an intern and resident at the Phipps Clinic at the Johns Hopkins Hospital in Baltimore (Harley and Weil, 1990).

At the Phipps Clinic, where Greenacre remained for twelve years, she came into contact with the great Swiss-American psychiatrist, Adolf Meyer. Her exposure to Meyer reinforced her conviction of the inextricable link between biology and psychology. In 1932 she began psychoanalytic training at the New York Psychoanalytic Institute, graduating in 1937. In 1942 she was appointed a training analyst and henceforth served in a number of important institutional positions at the Institute.