The early lay followers of St. Francis were probably known as the Order of Penance. That title expressed a conversion of life on the part of its members. Like Francis of Assisi, the members of the Order of Penance tried to carry the spirit of the gospel into their daily lives in the midst of their world and society.
Later these lay followers became known as the Secular Third Order of St. Francis. The word third distinguished the order from the First Order of St. Francis consisting of priests and brothers living in community with the three religious vows of poverty, chastity and obedience. It also distinguished the order from the Second Order of St. Francis, known as the Poor Clares, in which religious women lived a cloistered community life with vows of poverty, chastity and obedience. The word secular further distinguished the order from other groups of religious men and women belonging to religious orders observing a rule based on the Rule of St. Francis. When Pope Paul VI revised the lay or secular Rule of the Third Order, the official title became the Secular Franciscan Order.
The accent on secular is to make it clear the order is for people living in the mainstream of life. As Lester Bach, O.F.M., put it in Franciscan Way of Life: A Commentary on the Rule of the Secular Franciscan Order: “The secular Franciscans live in the world, i.e., not joined to or in convents, monasteries or friaries. The ‘place’ of holiness for Secular Franciscans is in the marketplace of the world, in the homes and neighborhoods where they dwell.“
The members of the Secular Franciscan Order are to infiltrate society from within. By their presence in its midst, they are to change society for the better. The title does not indicate that God is separate from society or the created world. It rather speaks of the desire of its members to make God ever more present to daily life.
Please see AmericanCatholic.org for the “Why Secular?” for the original article.