Tradesman's daughter from Siena, the younger the child belonged to middle-class large family (she was 25th child) dyer Benincasa di Jacopo (Giacomo di Benincasa, mind. 22 Aug, 1368) and monny paws de Piacente ( Lapa di Puccio di Piacenti), the daughter of artisans, manufactured sock for plows and wrote verses at the same time. Her father had secured the man and the whole family lived in his house, where the studio - in the quarter Fonte Brand (Fonte Branda). She was born in this house on the day of the Annunciation and also Palm Sunday - March 25, which was also the first day of Siena New Year. There was dead in infancy, twin sister of Giovanni. In addition, her parents took home 10-year-old orphan boy, apparently a relative of her husband Nikolett (sister of Catherine), zvavshegosya Tommaso della Fonte (fra Tommaso della Fonte), who later became a Dominican monk and was the first confessor of Catherine.
She had a cheerful and active character. At the age of seven years, according to his own story later, decided to dedicate his virginity to Christ (see below, section Visions). When in August 1362 suddenly died her beloved sister Bonaventura, it reinforced her aspirations. Her family forced her to marry, beginning with its 12 th birthday, but dedicated herself Catherine Lord, cut their hair, «it so much nagreshila and so hated». For nepokorstvo parents forced her to engage in all work at home, but in the end, the story of life, they caught her worshipers. Seeing as it descends upon the head of a dove, they realized that this is a sign of its purpose and ceased to obstruct.
Circa 1367 (exact date unknown), after long resistance to the family, she joined the Dominican Third Order «penitent sisters» (in Siena they were called to portable cloak - mantellaty; Mantellate) - that is, took the vows, not moved to the monastery. Her name in the list as Katerina Jacobi Benincasa. Community mantellatov consisted mostly of dignified widow, who at first had no desire to take a number of young damsel. During the following three years of his life she lived in a small room in the parental home alone, praying, reading the Scriptures and the writings of the holy fathers. These three years after taking a vow she had complied with the silence, talking only with his confession during the confessor. Also, she worked in hospitals, and leprosy. As indicated in this period, she had to endure hostility from prominent community mantellatok clergy and the church of San Domenico, which is not like the excessiveness of her spiritual heroism, and who did not believe in her ecstasy.
By some indications, Catherine has lost several brothers and sisters during the plague epidemic in 1374, and it developed its keen sense of human compassion. She dedicated herself to the daily care of the sick and poor, has been public affairs. Then she took not only nursing but also to missionary activity. Known as described by the very history, as it has come to the Lord sentenced to death by Nicolo di Toldo from Perugia (Siena, 1373, June; Penalty - October 15, 1379). Also among the hagiographic stories, reference should be made by the expulsion of a dying nun mantellatki Palmeriny demons with which she entered into a pact.