The Portiuncula Indulgence could at first be gained only in the Portiuncula chapel between the afternoon of 1 Aug. and sunset on 2 Aug. On 5 Aug., 1480 (or 1481), Sixtus IV extended it to all churches of the first and second orders of St. Francis for Franciscans; on 4 July, 1622, this privilege was further extended by Gregory XV to all the faithful, who, after confession and the reception of Holy Communion, visited such churches on the appointed day. On 12 Oct., 1622, Gregory granted the same privilege to all the churches of the Capuchins; Urban VIII granted it for all churches of the regular Third Order on 13 Jan., 1643, and Clement X for all churches of the Conventuals on 3 Oct., 1670. Later popes extended the privilege to all churches pertaining in any way to the Franciscan Order, even to churches in which the Third Order held its meetings (even parish churches, etc.), provided that there was no Franciscan church in the district, and that such a church was distant over an Italian mile (1000 paces, about 1640 yards). Some districts and countries have been granted special privileges. On 9 July, 1910, Pius X (only, however, for that year) granted the privilege that bishops could appoint any public churches whatsoever for the gaining of the Portiuncula Indulgence, whether on 2 Aug. or the Sunday following (Acta Apostolicae Sedis, II, 1910, 443 sq.; Acta Ord. Frat. Min., XXIX, 1910, 226). This privilege has been renewed for an indefinite time by a decree of the S. Cong. of Indul., 26 March, 1911 (Acta Apostolicae Sedis, III, 1911, 233-4). The Indulgence is toties-quoties, that is, it may be gained as often as one wishes (i.e. visits the church); it is also applicable to the souls in purgatory.
While the declarations of the popes have rendered the Portiuncula Indulgence certain and indisputable from the juridico-canonistic standpoint, its historical authenticity (sc. origin from St. Francis) is still a subject of dispute. The controversy arises from the fact that none of the old legends of St. Francis mentions the Indulgence, and no contemporary document or mention of it has down to us. The oldest document dealing with the Indulgence is a notary's deed of 31 October, 1277, in which Blessed Benedict of Arezzo, whom St. Francis himself received into the order, testifies that he had been informed by Brother Masseo, a companion of St. Francis, of the granting of the Indulgence by Honorius III at Perugia. Then follow other testimonies, for example, those of Jacob Cappoli concerning Brother Leo, of Fr. Oddo of Aquasparta, Peter Zalfani, Peter John Olivi (d. 1298, who wrote a scholastic tract in defence of this indulgence about 1279), Blessed John of Laverna (Fermo; d. 1322), Ubertinus of Casale (d. after 1335), Blessed Francis of Fabriano (d. 1322), whose testimony goes back to the year 1268, etc. In addition to these rather curt and concise testimonies there are others which relate all details in connection with the granting of the Indulgence, and were reproduced in numberless books: e.g. the testimony of Michael Bernardi, the letters of Bishop Theobald of Assisi (1296-1329) and of his successor Conrad Andreae (1329-37). All the testimonies were collected by Fr. Francesco Bartholi della Rossa in a special work, "Tractatus de Indulgentia S. Mariae de Portiuncula" (ed. Sabatier, Paris, 1900). In his edition of this work, Sabatier defends the Indulgence, although in his world-famous "Vie de S. François" (Paris, 1894), he had denied its historicity (412 sqq.); he explains the silence of St. Francis and his companions and biographers as due to reasons of discretion etc. Others seek to accord more weight to the later testimonies by accentuating their connection with the first generation of the order; others again find allusions to the Indulgence in the old legends of St. Francis. On the other hand, the opponents regard the gap between 1216 and 1277 as unbridgable, and hold that the grounds brought forward by the defenders to explain this silence had vanished long before the latter date. No new documents have been found recently in favour of the authenticity of the Indulgence.
[Note: The norms and grants of indulgences were completely reformed by Pope Paul VI after the Second Vatican Council in his Apostolic Constitution "Indulgentiarum Doctrina" (1967), and the Portiuncula Indulgence was again confirmed at that time. According to the Enchiridion Indulgentiarum, the Catholic faithful may gain a plenary indulgence on 2 August (the Portiuncula) or on such other day as designated by the local ordinary for the advantage of the faithful, under the usual conditions (sacramental Confession, Holy Communion, and prayer for the intentions of the Supreme Pontiff), by devoutly visiting the parish church, and there reciting at least the Lord's Prayer and the Creed. The Indulgence applies to the cathedral church of the diocese, and to the co-cathedral church (if there is one), even if they are not parochial, and also to quasi-parochial churches. To gain this, as any plenary indulgence, the faithful must be free from any attachment to sin, even venial sin. Where this entire detachment is wanting, the indulgence is partial.]
SOURCE: the Catholic Encyclopedia