Paragraph 152. From the Monday after the feast of the Baptism of the Lord until Lent and from the Monday after Pentecost until Advent there is a continuous series of thirty-four weeks in Ordinary Time.

This series is interrupted from Ash Wednesday until Pentecost. On the Monday after Pentecost Sunday the cycle of readings in Ordinary Time is resumed, beginning with the week after the one interrupted because of Lent; the reading assigned to the Sunday is omitted.

In years with only thirty-three weeks in Ordinary Time, the week immediately following Pentecost is dropped, in order to retain the readings of the last weeks which are eschatological readings.

The books of the Old Testament are arranged so as to follow the history of salvation: God reveals himself in the history of his people as he leads and enlightens them in progressive stages. This is why prophetic books are read along with the historical books, but with due consideration of the period in which the prophets lived and taught. Hence, the cycle of readings from the Old Testament contains, in Year I, the historical books and prophetic utterances from the Book of Joshua as far as, and including, the time of the exile. In Year II, after the readings from Genesis (read before Lent), the history of salvation is resumed after the exile up to the time of the Maccabees. Year II includes the later prophets, the wisdom literature, and the narratives in Esther, Tobit, and Judith.

The letters of the apostles not read at special times are distributed through the year in a way that takes into account the readings at Mass and the chronological order in which these letters were written.