The Pontifical Equestrian Order of St. Gregory the Great (Latin: Ordo Sancti Gregorii Magni; Italian: Ordine di San Gregorio Magno) was established on 1 September 1831, by Pope Gregory XVI, seven months after his election as Pope.^[1]

The order is one of the five orders of knighthood of the Holy See. The honor is bestowed upon Catholic men and women (and certain notable non-Catholics)^[2] in recognition of their personal service to the Holy See and to the Catholic Church, through their unusual labors, their support of the Holy See, and the examples they set in their communities and their countries.

The inaugural brief states, in part, that "gentlemen of proven loyalty to the Holy See who, by reason of their nobility of birth and the renown of their deeds or the degree of their munificence, are deemed worthy to be honored by a public expression of esteem on the part of the Holy See". The end of the brief states that they must progressively maintain, by continued meritorious deed, the reputation and trust they had already inspired, and prove themselves worthy of the honor that had been conferred on them, by unswerving fidelity to God and to the sovereign Pontiff.^[3]

The awarding of the Order of St. Gregory the Great presents no particular obligations on the recipients toward the Catholic Church – except for the general ones stated above.

An eight-pointed cross, the insignia of the order, bears a representation of St. Gregory on the obverse and on the reverse the motto Pro Deo et Principe ("For God and Ruler"). The cross is suspended from a red and gold ribbon. In ecclesiastical heraldry, laymen awarded the high rank of Grand Cross can display a red and gold ribbon surrounding the shield in their personal coats of arms, but the recipients of the lower ranks place an appropriate ribbon below the shield.^[4] The difference between the civilian and military insignia is that the former group wears the cross hanging from a green crown of laurel, whereas the latter group wears the cross hanging from a trophy of arms.^[5]

A green uniform was later prescribed by Pope Pius IX. The uniform contains a black beaver-felt hat decorated with black silk ribbons, silver metallic twisted rope, buttons and black ostrich feathers. The jacket, made of green wool, is trimmed with silver metallic thread, and has a tail, nine yellow metal buttons in the front and three buttons on the cuffs and is lined with black satin. Finally, the costume contains suspenders, several yellow and red rosettes, white leather gloves, and a short sword with a handle made of mother of pearl with a medallion of the order at the end.

Knights Grand Cross wear a sash and a badge or star on the left side of the breast; Commanders wear a cross around the neck; and Knights wear a smaller cross on the left breast of the uniform:

• Papal Orders of Knighthood