St. Louise de Marillac was born in Paris, France and was raised by her father. She was educated by the Dominican Sisters and was considered well educated for young women of her time.

Although she wanted to join a religious order, she was given in marriage to Antoine le Gras in 1611 and they had one child. During their marriage, they travelled and associated with the aristocracy and royalty of France. Antoine became ill and died in 1625.

After her husband died, Louise met and became friends with Vincent de Paul, who was working to serve the poor throughout France. Despite the fact that she had come from a background of wealth, she was just as comfortable around poor people. Louise dedicated her time to helping abandoned children on the streets. She also visited sick men in the prison hospital and established a house near the hospital where, each day, many women would cook food that visitors would then take to the prisoners.

Louise pushed the government to encourage every village to have its own clinic, school nurse and teacher. With Vincent, Louise started the Daughters of Charity in 1642. The Daughters of Charity were a revolutionary order of the poor. They helped abandoned children, people who were poor and sick, wounded soldiers, slaves, people who were mentally ill and the elderly. Today, there are over 20,000 Daughters of Charity, and they continue to help people in need.

Louise is the patron saint of sick people, widows and orphans, and in 1960, Pope John XXIII proclaimed her the Patroness of Social Workers.