About the Proper
From the Book of Divine Worship - The Proper: First Part
Concerning the Proper of the Church Year
The Proper of the Church Year includes the appointed Collect and Prayer over the Gifts for Sundays, Holy Days, and Various Occasions. It also contains some special propers. Unless otherwise indicated here, the readings at Mass for Sundays and weekdays are to be taken from the Lectionary of the Roman Missal, Revised by the Decree of the Second Vatican Council.
The Collect appointed for the Sunday is also used at celebrations of the Eucharist on the weekdays following, unless otherwise ordered for Holy Days and Various Occasions.
The Proper to be used on each of the Sundays after Pentecost (except for Trinity Sunday) is determined by the calendar date of that Sunday. Thus, in any year, the Proper for the Sunday after Trinity Sunday (the Second Sunday after Pentecost) is the numbered Proper (number 3 through number 8), the calendar date of which falls on that Sunday, or is closest to it, whether before or after. Thereafter, the Propers are used consecutively. For example, if the Sunday after Trinity Sunday is May 26, the sequence begins with Proper 3 (Propers 1 and 2 being used on the weekdays of Pentecost and Trinity weeks). If the Sunday after Trinity Sunday is June 13, the sequence begins with Proper 6 (Propers 1 through 3 being omitted that year, and Propers 4 and 5 being used in Pentecost and Trinity weeks).
The Collect appointed for any Sunday or other Feast may be used at the evening service of the day before.