Catherine was born in the Tuscan city of Siena in about 1347 and led a life of piety. At about the age of 20 she entered the Dominican Third Order, and underwent a series of spiritual experiences.
She attracted a group of followers and became involved in political matters when attempting to mediate between Tuscan cities and the Pope who was then in Avignon. Catherine persuaded Gregory XI to return to Rome, and then became involved with the subsequent schism of the Church, supporting Gregory's successor, Urban VI. She died in Rome in 1380 and was canonised in 1461.