Born on October 22, 1943 in Idaho Falls, Idaho, she was raised in Burbank, California. She was 16 years old when she entered Brigham Young University. She earned a bachelor’s degree in history with a minor in political science. She also obtained a teaching certificate in secondary education. In 1965 she married Noel B. Reynolds, whom she met at BYU.
Sydney and Noel Reynolds are the parents of eleven children. They live in Orem, Utah, but have lived in Boston, Massachusetts; Edinburgh, Scotland, and Jerusalem. She has served in many callings in the Church of Jesus Christ, including a member of the Primary General Board, early-morning Seminary teacher, Relief Society president, and ward and stake Young Women president. She served from 2005 to 2008 with her husband when he presided over the Florida Fort Lauderdale Mission. They served as president and matron of the Mount Timpanogos Utah Temple (2011–2014).
Reynolds has been involved in her community as well. She was a member of the Timpanogos Storytelling Festival organizing committee, the BYU Women’s Conference steering committee, and PTA president.