As soon as the Church obtained her freedom in the fourth century, the faithful in Jerusalem re-enacted the solemn entry of Christ into their city on the Sunday before Easter, holding a procession in which they carried branches and sang the "Hosanna" (Matthew 21: 1-11). In the early Latin Church, people attending Mass on this Sunday would hold aloft twigs of olives, which were not, however, blessed in those days.

The rite of the solemn blessing of "palms" seems to have originated in the Frankish kingdom. The earliest mention of these ceremonies is found in the Sacramentary of the Abbey of Bobbio in northern Italy (at the beginning of the eighth century). The rite was soon accepted in Rome and incorporated into the liturgy. A Mass was celebrated in some church outside the walls of Rome, and there the palms were blessed. Then a solemn procession moved into the city to the basilica of the Lateran or to St. Peter's, where the pope sang a second Mass. The first Mass, however, was soon discontinued, and in its place only the ceremony of blessing was performed.

Everywhere in medieval times, following the Roman custom, a procession composed of the clergy and laity carrying palms moved from a chapel or shrine outside the town, where the palms were blessed, to the cathedral or main church. Our Lord was represented in the procession, either by the Blessed Sacrament or by a crucifix, adorned with flowers, carried by the celebrant of the Mass. Later, in the Middle Ages, a quaint custom arose of drawing a wooden statue of Christ sitting on a donkey (the whole image on wheels) in the center of the procession. These statues (Palm Donkey; Palmesel) are still seen in museums of many European cities.

As the procession approached the city gate, a boys’ choir stationed high above the doorway of the church would greet the Lord with the Latin song Gloria, laus et honor. This hymn, which is still used today in the liturgy of Palm Sunday, was written by the Benedictine Theodulph, Bishop of Orléans (821):

Glory, praise and honor, O Christ, our Savior-King, To thee in glad Hosannas Inspired children sing.

After this song, there followed a dramatic salutation before the Blessed Sacrament or the image of Christ. Both clergy and laity knelt and bowed in prayer, arising to spread cloths and carpets on the ground, throwing flowers and branches in the path of the procession. The bells of the churches pealed, and the crowds sang the "Hosanna" as the colorful procession entered the cathedral for the solemn Mass.

In medieval times this dramatic celebration was restricted more and more to a procession around the church. The crucifix in the churchyard was festively decorated with flowers. There the procession came to a halt. While the clergy sang the hymns and antiphons, the congregation dispersed among the tombs, each family kneeling at the grave of relatives. The celebrant sprinkled holy water over the graveyard, the procession formed again and entered the church. In France and England the custom of decorating graves and visiting the cemeteries on Palm Sunday is still retained.

Today the blessing of palms and the procession are usually performed within the churches. The new liturgical arrangements made by Pope Pius XII have restored the original solemnity of the procession, and the members of the congregation now take active part again in the sacred ceremonies of Palm Sunday. The blessing of palms, however, is now very short and simple compared to the former elaborate ritual.

(FromHandbook of Christian Feasts and Customsby Francis X. Weiser, S.J., Harcourt, Brace and Company, New York, 1958)