The First Class contain only one category, who take religious vows of poverty, chastity, and obedience and form what amounts to a religious order, and three surviving cloistered monasteries of nuns of the Order, two in Spain that date from the 11/12th centuries and one in Malta, whose members hold the same rank in the Order as chaplains.

They are under obedience to the Holy See directly because they are religious.

The far more numerous Second Class: Knights and Dames of Honour and Devotion in Obedience, Knight and Dames of Grace and Devotion in Obedience, and Knight and Dames of Magistral Grace in Obedience; Third Class: Knights and Dames of Honour and Devotion, Conventual Chaplains ad honorem, Knights and Dames of Grace and Devotion, Magistral Chaplains, Knights and Dames of Magistral Grace, and Donats (male and female) of Devotion are not religious.

The Grand Master and the heads of the six Grand Priories are not First Class.