Groups of penitents existed before the Franciscans, and from the beginning, Francis and his brothers identified themselves as penitents from Assisi. Many individuals in these penitent groups desired to be associated with Francis and the brothers, and from this emerged what might be called the Franciscan penitential movement and eventually the Third Order. In a spontaneous response to Francis’ teaching about conversion, members of every social class were moved to a change of heart, to renounce sin and turn away from worldly concerns to serve the Lord in all states of life: cleric, religious, and lay. As Francis and the brothers reached out to them with admonitions and instructions on how to live the Gospel, groups of devout souls began to gravitate to the churches where the friars were located, turning to them for counsel, seeking a deeper understanding of the spiritual life.
The preaching and example of St. Francis exercised such a powerful attraction for people throughout Italy that many of the laity began to desire a deeper experience of God. Because they were bound by family responsibilities, Francis encouraged them to begin leading a Gospel-rooted life in their own homes or places of work, thus inspiring a new “third order” for the universal salvation of all people. Francis admonished them to live simply within the bonds of marriage, or singly, and to love and serve the Lord by serving their neighbor and participating more fully in the life of the Church.
—from the book Franciscan Field Guide: People, Places, Practices, and Prayers
by Sister Rosemary Stets, OSF