Her parents were the Count Marcantonio Marescotti, who claimed descent from one Marius Scotus, a military leader under the Emperor Charlemagne, and Countess Ottavia Orsini, whose father had built the noted Gardens of Bomarzo.

In her early youth, Clarice had been noted for her piety, but, as she grew older, she became frivolous, which not even an almost-miraculous saving of her life at the age of 17 could change, nor her education at the monastery.

[1] At the age of 20 Clarice set her heart upon marriage with the Marchese Capizucchi, but was passed over by him in favor of her younger sister, Ortensia.

At that point, due to a severe illness, the priest who served as the confessor to the monastery went to her cell to bring her Holy Communion.

She gave away her costly garments, wore an old tunic, went barefoot, frequently fasted on bread and water, and chastised her body by vigils.

One of these, similar to the Society of St. Vincent de Paul, gathered alms for the convalescent, for the poor who were ashamed to beg, and for the care of prisoners; the other procured homes for the aged.