Amy met Tim while attending Wake Forest University in North Carolina. Tim played basketball, while Amy was a cheerleader.

Amy married Tim in the summer of 2001. The couple had their first child, daughter Sydney in the summer of 2005, and their second child, a son, during the summer of 2007. Amy oversees the Tim Duncan Foundation, which has been established to serve the areas of health awareness/research, education, and youth sports/recreation in San Antonio, Winston-Salem, and the United States Virgin Islands. Amy Duncan serves as the executive vice president of the organization.