When Do I Sit, Stand or Kneel?

A lot of people  come to the Latin Mass for the first time and they are not sure what the correct posture is for the different parts of the Mass.  Even some experienced Mass attendees are confused.   This is especially true for the low Mass as there are differences.  The following is  what this writer has seen in Southern California.   As a general rule you stand when  the altar server is standing, and likewise kneel when he kneels.  

Low Mass

At a low Mass you stand for the entrance of the priest, then you kneel when he begins the Mass until the reading of the gospel at which point  you stand.   You do not stand every time the priest says, "Dominus Vobiscum."  like you do at a high Mass.  You then sit until the Credo if there is one and then remain seated until the Sanctus for which you kneel.   Remain kneeling until the end of Mass.  If you need to you can sit during communion, but kneeling is recommended.  When the priest announces the last gospel you stand.

High Mass or Missa Cantata

The sung Mass is different as there is more standing.  This hearkens back to the days when churches had no pews.  If you can remember to stand every time the priest sings, "Dominus Vobiscum." you'll look like you know what you're doing!     You stand for the priest's entrance and then  the Asperges, if there is one.  You then  kneel for the prayers at the foot of the altar.  You stand as the priest intones the Gloria in Excelsis Deo.  Remain standing until the priest starts to chant the epistle during which you sit.  Stand for the Gospel and the Credo.  After the sermon you remain seated and then stand when the server incense the congregation.  You stand again when the priest sings, "Dominus Vobiscum." then kneel at the Sanctus.  When the priest announces the Pater Noster you stand, and then you kneel at the Agnus Dei.   Remain kneeling through communion if possible and then stand when the priest says, "Dominus Vobiscum." to finish the Mass.