Born in Seattle in 1929, Baer attended the University of Washington from 1946- 1949, where she majored in biology. She completed graduate work in physiological psychology at the School for Social Research in New York before moving to Los Angeles in 1953. It was here that she would begin her artistic career, eventually returning to New York in 1960.
Baer's first solo show took place at the Fischbach Gallery in New York in 1966 and in 1975, during the height of her career, a retrospective of her work was held at the Whitney Museum of American Art, following which she would immigrate to Ireland. A more recent retrospective of her work was held at the Stedelijk Museum in Amsterdam, where she has lived and worked since 1983.