Cooper retired from the stage in the early 1960s after developing a spinal-cord tumor which left her paralyzed for a couple of years. She underwent surgery which enabled her to walk again and then began a second career as a voice teacher. She taught on the voice faculty of Montclair State University for more than two decades, after which she taught voice privately out of her home up until her death in 2008. Cooper was married to Harold Cooper, an industrial machinery salesman, from 1946 until Harold's death in 1993. The couple had two sons, David and Thomas, both of whom became medical doctors. A longtime resident of Teaneck, New Jersey, she died on 3 April 2008 at the age of 92.[3]