The Mishnah commences with an account of the four beginnings of the religious and the civil year (1:1); it speaks of the four judgement-days of the pilgrim festivals and Rosh ha-Shanah (1:2); of the six months in which the messengers of the Sanhedrin announce the month (1:3); of the two months, the beginnings of which witnesses announce to the Sanhedrin even on the Sabbath (1:4), and even if the moon is visible to every one (1:5); Gamliel even sent on the Sabbath for forty pairs of witnesses from a distance (1:6); when father and son (who as relatives may otherwise not witness together) behold the new moon they must set out for the beth din (1:7), since they do not absolutely belong to those that are legally unfit for this purpose (1:8).

The weak and sick are borne on litters, and are protected against the attacks of the Sadducees; they must be provided with food, for witnesses were bound to journey even on the Sabbath (1:9).

There were various obstacles to the sanctification of the months, as when time was lacking for the ceremony, or when there were no witnesses present before the bet din.

The Mishnah discusses also the laws of the shofar (3:2); the horn of the cow may not be used (3:2); the form of the trumpet for Rosh haShanah, the fast-day, and Yovel is determined (3:3–5); damage to the shofar and means of repair are indicated (3:6); in times of danger the people that pray assemble in pits and caves (3:7); one passing a synagogue who hears the shofar fulfills his obligation only if he intended to fulfill it (3:7); they are exhorted to be firm by being reminded of Moses' uplifted hands in the war with the Amalekites (3:8).

The Mishnah then discusses of the order of Rosh Hashanah Mussaf prayers (4:4); of the succession of the Malkhuyot, Zikhronot, and Shofarot; of the Bible verses concerning the kingdom of God, Providence, and the trumpet-call of the future (4:5), and of the leader in prayer and his relation to the teki'ah (4:6); descriptions of the festival are given in reference to the shofar (4:7); then follows the order of the traditional trumpet-sounds (4:8); and remarks on the duties of the leader in prayer and of the congregation close the treatise (4:9).

Curious as is the order of subjects followed in this treatise, in which several mishnaic sources have been combined, the Tosefta follows it, adding comments that form the basis of the Gemara in both Talmuds.

The dignity of the nasi is not emphasized, because acumen and scholarship prevailed in the schoolhouse, and there was no desire to let old precedences (see Eduyot) come to the fore again.