The Third Order Regular of St. Francis of Penance (or Third Order Regular of St. Francis) is a mendicant order rooted in the Third Order of St. Francis which was founded in 1447.
The twelfth century saw a marked emphasis toward the penitential life, reflected in monastic reforms of Romuald (+ 1027), and Peter Damian among others. The Third Order Regular developed from the Third Order Secular movement which arose in the early 13th century from the convergence of groups of penitents who were inspired by the life of Francis of Assisi. Sometime between 1209 and 1220, Saint Francis communicated with some of these groups through a series of letters entitled the "Exhortations to the Brothers and Sisters of Penance". In 1221 Francis asked Cardinal Ugolino di Conti to draft a rule for lay people whose personal circumstances precluded their joining a religious order such as the Friars Minor or the Poor Clares. These individuals formed the Third Order of Saint Francis and were called "tertiaries".
The organized form of this life, though, can be more reliably traced back to the second half of the thirteenth century. In 1289 the first Franciscan pope, Pope Nicholas IV decided to recognize the Third Order of San Francis in a formal manner. He gave approval to the Order of Penance, and reissued the “Memoriale Propositi”, the Rule of 1221 in a more juridic form. Those Penitent Franciscans who remained in their homes (married or single) constituted the Secular Third Order (TOS), which since 1978 has been called the Secular Franciscan Order (OFS).
Some secular tertiaries, who in many cases had their house of meeting, gradually withdrew entirely from the world and so formed religious communities, but without the three vows of religious orders. Some of the penitents began to live communal life dedicating themselves to works of mercy; others began to live in remote places as hermits. Members of religious organizations, such as the Beguines (women) and Beghards (men) in the Low Countries, sometimes joined the Third Order. These groups were known as the Religious of the Third Order Regular of St. Francis.