Louise de Marillac was born in Paris in 1581, out of wedlock. She was acknowledged by, and provided for, by her father, Louis de Marillac, but never knew who her mother was. At a very young age, she was placed in the Abbey of Poissy to be educated with other children of noble birth. When she was around 12, her father died and Louise was sent to a Paris pension operated by a poor lady. There, she performed daily housekeeping chores and organized the other girls in performing handiwork for sale to help with the upkeep of the pension.

Although Louise expressed interest in a cloistered life, the Religious superiors with whom she consulted did not feel she had that vocation. Early in 1613, she was married to Antoine le Gras, secretary to the Queen Mother, Marie de Medici. Louise and Antoine experienced happiness in their marriage, and before the end of the year were blessed with the birth of their son, Michel Antoine. Born prematurely, Michel was both delicate in health and somewhat slow in learning. In 1621 Antoine became ill with a disease from which he never recovered, and the family's financial circumstances worsened severely. Louise fell into depression. On the feast of Pentecost, June 4, 1623, while at prayer, she had a vision in which she saw herself serving the poor and living in a religious community. She wrote this lumière, or Pentecost experience, on parchment and carried it with her as a reminder that, despite her difficulties, God was guiding her life. In that vision a priest appeared to her, whom she laster identified as Vincent de Paul. Antoine died in December, 1625

Louise endeavored to cope with her continued trials through prayer, sacrifices, and the advice of wise directors. Her regular spiritual director was Bishop Camus. In 1619, Louise met Francis de Sales, whose books had become a staple of her spiritual reading. In 1623, Bishop Camus was moved to a diocese outside of Paris, and he recommended Vincent de Paul as Louise's spiritual director. It seems that both Vincent and Louise had initial reservations: Vincent because he had found difficulty directing other noblewomen, and Louise because of the difference in their social station.

While at prayer during one of her darkest periods, Louise had a vision in which she saw herself serving the poor and living the vows of a religious in community. She wrote this lumiere on parchment and carried it on her person as a reminder that, despite her difficulties, God was guiding her life. In that vision a priest appeared to her, whom she later identified as Vincent de Paul.

In 1629, Vincent, who had established the Congregation of the Mission (the Vincentians) in 1625, invited Louise to assist him with the Confraternities of Charity in the parishes of France. Through this work, she gained a deep knowledge of the needs of the poor, developed her own innate management skills, and identified effective structures for service.

In 1630 Vincent began sending girls to Louise to be trained to work under the direction of the Ladies of the Confraternities of Charity. By the next year, Louise petitioned Vincent that she dedicate all her time and energy to forming young servants of the poor; however, Vincent had reservations, and asked her to wait. In 1633, Vincent told Louise that intensive prayer was called for concerning her future ministry. Following his annual retreat, he gave his full approval to her consecrating all her energies to this new undertaking.

Immediately, in her own home, she began to train young women to address the needs of the poor and to gain support from their life together. From this humble beginning, the Daughters of Charity emerged. Louise provided leadership and expert management to the evolving network of services she and Vincent inspired.

At first the Daughters of Charity assisted the Conferences of Charity in the Paris area by preparing food and medicine which they would bring to the sick poor in their homes. As their reputation spread, they were asked to take over hospitals, the care of foundlings, ministry to the galley convicts, and nursing the wounded on battlefields . . . schools and institutions for elderly followed.

Actually, the Daughters of Charity functioned as a religious community for decades, before Vincent and Louise sought canonical approval from the Church. At that time religious communities of women were cloistered, but Vincent and Louise saw these women as working among the poor. Vincent told the Sisters: "You must have no other monasteries than the houses of the poor; no other cloisters than the streets of the cities and the wards of hospitals; no other veil than your modesty; you must treat the sick and the suffering with all the care and tenderness that a mother lavishes on her only son." However, Vincent knew that, not long before, Francis de Sales had envisioned the Visitation Sisters as working in the world, but they found themselves behind cloistered walls. Because the Daughters of Charity had worked in the world for decades when Vincent applied for their canonical recognition, they were permitted to continue and became the first non-cloistered community of religious women.

Louise, who died on March 15, 1660 just a few months before Vincent de Paul, was proclaimed a Saint of the Church in 1934. In 1960 Pope John XXIII proclaimed her the Patroness of all Social Workers. As a wife, mother, teacher, nurse, social worker and religious foundress, she stands as a model to all women.