Ms. Kerr was 80 and lived in Larchmont, NY, in the Westchester County that is the setting for her 1957 book of domestic suburban adventures, "Please Don't Eat the Daisies," which was later made into a film and a TV series. The cause of her death was pneumonia.
On Broadway, she scored a major hit with Mary, Mary, in 1961. The comedy concerned a divorced couple who decide they are right for each other after all. The play ran more than 1,500 performances and was made into a film.
The Times reported that Ms. Kerr was born in Scranton, PA, and attended Marywood Seminary and Marywood College there. She married Kerr after earning a bachelor's degree at Marywood and then earned at master's degree at Catholic University, where Walter Kerr was a professor. They would go on to collaborate as writers on shows, and he would become the respected drama critic for The New York Times (the former Ritz Theatre on Broadway is named after him).
Together, the Kerrs penned Song of Bernadette, a stage version of a novel about Saint Bernadette of Lourdes, for Broadway in 1946. The also collaborated on an unsuccessful revue, Touch and Go, in 1949, writing lyrics and sketches. The married couple also wrote material for the revue, John Murray Anderson's Almanac in 1953.
Ms. Kerr's solo playwriting efforts included Jenny Kissed Me, Poor Richard, Finishing Touches and Lunch Hour, which starred Gilda Radner and Sam Waterston. The Times reported that the Kerrs had such an unhappy experience with their flop musical, Goldilocks, starring Elaine Stritch, that they "made a mutual vow never to mention its name again." But time has been kind to that 1958 musical comedy with music by Leroy Anderson, book by the Kerrs and lyrics by the Kerrs and Joan Ford. The cast album, re-released on CD in recent years, is beloved by show fans and includes the memorable ballad, "I Never Know When."
Ms. Kerr is survived by sons Christopher, Colin, John, Gregory and Gilbert, and daughter Kitty.