The preaching of St. Francis, as well as his example, exercised such a powerful attraction on people that many married men and women wanted to join the First or the Second Order, but this being incompatible with their state of life, Francis found a middle way and gave them a rule animated by the Franciscan spirit. In the composition of this rule St. Francis was assisted by his friend Cardinal Ugolino di Conti, (later Pope Gregory IX).

The earliest Rule was found in the Guarnacci Library in Volterra. This primitive document is known as the Earlier Exhortation, or the Earlier Version, of "The Letter to All the Faithful" and was likely composed before 1215. An expanded version, the Later Exhortation, was completed by about 1220. Both have been established as having been composed by Francis. Both documents call the lay faithful to a life of penance, i.e., of turning away from sin and toward God.