According to the Missal, the Glory to God is prescribed for Feasts and Solemnities, but not for memorials of any kind.

For example, this Friday the Gloria isn't recited (Memorial of Andrew Kim Tae-gon and Companion Martyrs), but on Saturday it is (Feast of St. Matthew, Apostle and Evangelist).

(BTW, thanks for the reminder to remind my pastor that the Gloria is sung at this Saturday's morning Mass!)

GIRM 53 says that the Gloria "is sung or said on Sundays outside Advent and Lent, and also on Solemnities and Feasts, and at particular celebrations of a more solemn character." As Aristotle says, not on Memorials.

I looked through the entire Ordo (for the province of Massachusetts), and I must admit to being shocked (in a bad way) as to how few Saints' days are Feasts, and they seem only to include the Apostles, Chair of Peter, St Lawrence, and a couple others. Most saints are optional memorials - no wonder the idea of the cultus of the saints is irrelevant to most people's spiritual lives!

Of course, if your parish and/or church is dedicated to St Swithen Wells (10th December) you are to celebrate his feast as a Solemnity, including the Gloria, even if he's not on the General Calendar. (And you can gain a plenary indulgence for participating in Mass that day.)

Salieri,

I wouldn't characterize the placement of saints as optional memorials as downplaying the importance of saints, so much as an attempt to maintain a normal lectionary cycle. There would be no need for a day-to-day lectionary at all if all saints' days were obligatory, and much of the Bible would be missed at Mass.

In addition to "Sundays outside the Seasons of Advent and Lent, on solemnities and feasts, and at special celebrations of a more solemn character," as Fr. Ron Krisman cites above, the Gloria is now done at almost all ritual Masses, even in Advent or Lent.

P.S. You may celebrate St. Swithen Wells as a Solemnity even in Advent, except if he falls on a Sunday; Sundays of Advent, Lent, and Easter are higher on the table of precedence than most Solemnities (strangely enough, Sundays of Christmas aren't!).

Contrary to what I used to think, not only can your parish's patron saint (or titular saint, or anniversary of dedication) be celebrated as a Solemnity, even on Sundays in Ordinary Time, but a pastor may even move said celebration to the nearest Sunday in Ordinary Time so that the parishioners may more easily participate.

Andrew makes a number of good points, particularly what he says in his final paragraph.

I would have a slight disagreement with his first paragraph (and some agreement with Salieri's second paragraph). The General Norms for the Liturgical Year and Calendar are quite clear that a heightening of the importance of the temporal cycle and of Sunday as the primordial feast day, and a lessening of the importance of the sanctoral cycle were some of the principles which guided the reform of the General Roman Calendar in 1969.

These efforts were not designed to downplay the cultus of saints but, rather, to recognize that where there is no true cultus for a particular saint we should not pretend that there is.

And, it should be noted, this impulse is not novel in the Church. There was a considerable simplification of the calendar before, such as after Trent; it's a tide that waxes and ebbs over time.