In 1984 Karen Stives made Olympic history when she became one of the first two females to win an Olympic individual medal in eventing. Stives won silver at the Los Angeles Olympics, followed by British rider Virginia Holgate, who won bronze. It was not an upset for Stives, who had been USCTA Rider-of-the-Year in 1981, and had competed well at the 1982 World Championships aboard her thoroughbred, The Saint. After that competition she purchased Ben Arthur, the horse she rode in Los Angeles, and with which she made her best known pairing, before retiring him in 1986. Stives would again be named USCTA Rider-of-the-Year in 1987 and 1988.
Stives retired from competition in the early 1990s and became an international and national level judge. She also chaired the US Equestrian Team selection committee for 10 years. In 2006 Karen Stives was inducted into the US Eventing Association’s Hall of Fame. For 25 years she was the owner and President of The Barn Family Shoe Store in West Newton, Massachusetts. In 2014, shortly before her death from cancer, she donated $1 million to the US Equestrian Team Foundation, which funds competition grants to US riders and became known as the Karen E. Stives Endowment Fund for High Performance Eventing. A graduate of Dana Hall School and Manhattanville College, after her death the Karen Stives Center was named for her at Dana Hall.