St. Vincent de Paul (1581 - 1660) worked with St. Louise de Marillac (1591 – 1660) in organizing hospitals for the poor, asylums for the orphaned, workshops for the unemployed, and championing literacy for the uneducated. For his work he became known as "The Apostle of Charity" and "Father of the Poor."

There has always been a debate within Christianity over whether faith in Jesus Christ alone is sufficient for salvation, or whether this faith must - as is the belief of Roman Catholicism - be accompanied by works.

Yes, we know about your clergy and nuns working with the poor, but what are you and your Catholic friends in this room doing about the poor? Show us your works. - question posed to Frederick Ozanam during an informal college debate while attending the University of Sorbonne
Spurred by this challenge, Frederic Ozanam (1813-1853) decided to start an organization devoted to charitable work with the poor. On April 23, 1833 - together with several of his fellow students and friends - Ozanam founded the Conference of Charity. It was only natural that the group should take as its patron St. Vincent de Paul and shortly the name was changed to reflect this - The Society of St. Vincent de Paul.

The Society is a lay organization that is not only a relief organization, but a spiritual Society whose members seek to sanctify their own lives by serving and assisting and administering to the poor and unfortunate. Today the Society has over one-million volunteers in 132 countries. The first American chapter was founded in St. Louis, Missouri in 1845 - making it the oldest Catholic lay organization in the United States.

In my personal experience, almost every American city or town has a St Vincent de Paul thrift store. These are similar to the ones run by Goodwill Industries or the Salvation Army. People donate clothing and household items that are resold at low prices. As a child I visited all three on a regular basis as part of my mother's shopping trips. They are an invaluable resource for the poor and indigent.

Sources:
http://www.svdpusa.com/
http://www.myparish.net/svp/Founder.htm
http://www.rc.net/providence/stbartholomew/svdp.html