St. Louise de Marillac was born in 1591 in Paris France. After the death of her father, she was placed in a boarding house in 1604 where she learns practical skills which will be needed later for charitable works.

In February of 1613, St. Louise was married to Antony LeGras. In October of that same year, she gave birth to a son. In 1625 Antony died after a long illness. It was during that illness that St. Louise met St. Vincent de Paul. St. Vincent became St. Louise's spiritual advisor. They shared a strong devotion to the sick and the poor of Paris. This devotion was so strong that it lead to the foundation of the Daughters of Charity.

After the foundation of the Daughters of Charity in 1633, Louise assumed responsibility for the Sisters’ spiritual and professional formation. St. Louise spread her healing ministry to the whole of France and lead the Sisters to hospitals and orphanages. They cared for the poor and the homeless. They cared for prisoners and slaves. If there was a need in the community, St. Louise and the Daughters of Charity fed that need.

Since the time of St. Louise's death in 1660, the ministry that she and St. Vincent de Paul founded has flourished. It has spread from humble roots in Paris, France to minister to the need of people all over the world.

St. Louise was canonized by Pope Pius XI in 1934, and was declared Patroness of Social Workers by Pope John XXIII in 1960.