Judy-Lynn was friends with Lester del Rey and married him after the death of his third wife. After moving to Ballantine Books, she revitalized the publisher's once-prominent science fiction line there, and soon after brought in Lester to edit Del Rey's fantasy line. With their success, she was given her own imprint, called Del Rey Books. She also edited an original sf anthology series, Stellar. As an editor, she was known for her rapport with authors and beloved reputation. She was also instrumental in obtaining the rights to publish novels based on George Lucas's then un-released movie Star Wars, which would earn Ballantine/Del Rey several million dollars.
She suffered a stroke in October 1985 and died several months later. In 1986, she was posthumously awarded the Hugo Award for Best Professional Editor, but Lester del Rey declined the award in her name, saying that she would have objected to the award being given to her just because she had recently died.