St. Therese of the Child Jesus, "the greatest saint of modern times" according to the pope who canonized her, is commemorated today.
Her feast is technically not a feast but a memorial. As such, only certain parts of her are obligatory--from the reading and onward in the the commons of saints. Your breviary--and the digital ones that I checked--both use the common of virgins. However, since St. Therese was proclaimed a doctor of the church in 1997 by Pope John Paul II, this is now another option. My opinion is that the prayers of the common of virgins work better for Therese, since their theme is love, and that is what this saint's "doctoral" writings are all about.
Now, I said that an obligatory memorial only obliges one to use the saint's prayer and common from the reading onward, but you can be sure that in the Carmelite order they are celebrating this as a feast, with the psalmody of a feast rather than a weekday, e.g. Sunday Week I will be used for Morning Prayer psalmody. (If my Carmelite reader is following this today, I hope she will confirm that for me.)
I think, by extension, anyone who has a particular devotion to a saint, and considers him or her to be a special personal patron, may celebrate a memorial as a feast, or even a solemnity (with an Evening Prayer I), so long as it does not occur on a Sunday or a solemnity. The General Instruction on the Liturgy of the Hours has a long list of which days take precedence over which. It's a tad confusing, but the sense I get from it is that a saint who is in some sense special to you may be given the full liturgical treatment if you like.
That being said, I just remembered--you can't do Saturday evening prayer for St. Therese, because Sunday evening prayer I for the 27th Sunday in ordinary time takes precedence.
