Agnes Day was born in 1933 and grew up in the Philippines, with the exception of 1940–1944 when she was living with relatives in the United States while her parents and one sister were in the concentration camp of Santo Tomás in Manila. They survived, the family was reunited, and, after a period of rest in the US, returned to the Philippines. When her mother became a Catholic, Agnes followed her on this path during her second year at Middlebury College. Four years later, in 1956, she entered Mount Saint Mary's Abbey in Wrentham, Massachusetts. She was prioress there for nine years, as well as vocations director, secretary to the abbess, and community cobbler. In 1986 she was elected abbess, serving the community in that capacity for twenty-two years. Since 2008, she has been happily living her Cistercian vocation once again as a simple sister.