Catherine has a younger sister, called Christina Oxenberg, who is a writer. She also has a half-brother, Nicholas Balfour.
In July 1998, Catherine was briefly married to the film producer Robert Evans - they were married and divorced in less than two weeks.
She is an old flame of U.S. Senator John Kerry, who was the Democratic Party's presidential candidate in 2004.
She has three daughters, India Oxenberg (born 1991), Maya van Dien (2001) and Celeste Alma van Dien (2003).