337. The vestment proper to the Priest Celebrant at Mass and during other sacred actions directly connected with Mass is the chasuble worn, unless otherwise indicated, over the alb and stole.
I’m not sure how the stole came to be worn over the chasuble by a majority of clergy. It seems a rather minor point, but the GIRM is clear, as we read.
338. The vestment proper to the Deacon is the dalmatic, worn over the alb and stole; however, the dalmatic may be omitted out of necessity or on account of a lesser degree of solemnity.
I see more dalmatics these days here in the Midwest. What about you?
339. In the Dioceses of the United States of America, acolytes, altar servers, readers, and other lay ministers may wear the alb or other appropriate and dignified clothing.
Except for child, teen, and young adult servers (seminarians) and the very occasional choir, the alb is very rare for lay ministers. “Appropriate and dignified clothing” is far more common.
340. The stole is worn by the Priest around his neck and hanging down in front of his chest, while it is worn by the Deacon over his left shoulder and drawn diagonally across the chest to the right side, where it is fastened.
341. The cope is worn by the Priest in processions and during other sacred actions, in accordance with the rubrics proper to the individual rites.
I’ve seen the cope worn at the Rite of Election and the occasional wedding outside of Mass, though a chasuble seems more appropriate for either liturgy. Good Friday, a bit more common. Eucharistic Benediction, maybe more frequently.
What are you seeing on the backs of liturgical ministers, especially the clergy, in your church?