Mary Beatrice d'Este was the older child of Alfonso IV, Duke of Modena and his wife Laura Martinozzi. She was born on 5 October 1658 NS in Modena. Her only sibling, Francesco, became a Duke when his father died in 1662. This was the year Mary became 4. Mary and Francesco's mother Laura was firm with her children. She acted as regent of the duchy until her son grew older. Mary's education was very good. She spoke French and Italian well, and had a knowledge of Latin and, later, English.