For as long as there have been men and women of God who sought Him with all of their hearts and grew in wisdom and sanctity, there have been other men and women who felt called to follow them, learning from their teaching and their example. This was true even in Old Testament times, e.g. the men spoken of in the Books of Kings as those who gathered around Elijah and Elisha. The Fathers of the Desert, who went to the wilderness to pray and let God have His way in their hearts, were frequently joined by other men who wanted to be led closer to God as well.

This became particularly common in the lives of the great Saints who founded religious orders: e.g. St. Benedict, St. Dominic, St. Francis, and St. Teresa of Jesus. Though some felt the call to formally join their religious orders as priests, brothers, and nuns, there were always men and women who, for a variety of reasons, felt called to participate in the lives of these Saints and their religious orders, but to do it while remaining 'in the world.'

St. Francis of Assisi was the first religious founder to formally begin a Third Order in his religious community, providing his Third Order with a Rule, i.e. a written way of life to follow that incorporated his own special charism.

Eventually, as a way of sharing their lives as well as more concretely caring for these folks' spiritual needs, more and more Orders developed their own Third Orders, e.g. the Augustinians, the Benedictines, the Carmelites, the Franciscans, etc. These are composed of lay men and lay women and secular (diocesan) clergy who wish to participate formally in these different religious communities, sharing in their charism, joining in their prayer, having their lives molded by the teaching and example of their Founders, joining in their apostolate, etc. while remaining 'in the world.'

These Third Orders have come to be looked at as 'schools of sanctity,' teaching a particular approach to holiness and union with God based on the charism and teaching of their particular founder. Both of the Orders of Carmel (the O. Carms. and the O.C.D.'s) have Third Orders.

As different religious orders, following the direction of the Second Vatican Council, reflected on their identity and charism, a slight change came about that concerned the Third Orders. Taking up the Council's teaching on the dignity and apostolate of the laity, and their particular charism to be in the world but not of the world, transforming the world by their presence and labors in its midst, a name change was seen as appropriate concerning the Third Orders. They are now more generally termed 'secular' orders. 'Secular' understood not in the pejorative sense of 'worldly' but in the Gospel sense of having a mission to be in the world. The mission of the members of the secular orders is to take the particular graces and charisms of their respective religious communities and share them with others in the world.