Do I interrupt Davening to say Shema with the Minyan?
We should always join the tzibbur (congregation) in the proclamation of Hashem’s Oneness and say Shema with the minyan (prayer quorum). What are the parameters of this obligation?
What must be said: The requirement is to say the first pasuk (verse) of Shema, followed by the phrase Baruch Shem. If it is the Shema of Shacharis or Maariv, we should cover our eyes in the usual manner. It’s mentioned by poskim that it is “tov” (good) to complete all three paragraphs of Shema, and thus receive schar (Divine reward) as one who reads from the Torah, but this is not the common custom.
When it must be said: When a latecomer to shul finds that the minyan (prayer quorum) is in the midst of reciting Shema—whether it is the Shema of Shacharis or Maariv, of Kedushah in the Mussaf repetition, or when the Torah scrolls are being taken from the Aron (ark), he should join in.
If davening at a different pace than the minyan, we should nevertheless recite the first pasuk of Shema with the minyan. However, if we have begun saying Pesukei D’zimrah there is a dispute among poskim whether it should be followed by Baruch Shem… as that phrase may be considered a hefsek (disruption).
When saying the brachos preceding Shema we may not interrupt at all, but should still give the appearance of joining the recital by saying the words of tefillah (prayer) in the familiar tune of Shema.
What else should be said: Poskim say that the Aleinu prayer and the yud-gimmel midos HaRachamim (thirteen G-dly attributes) should also be said together with the minyan out of respect for their significance. It is brought in Shulchan Aruch, in a tradition going back to the Geonim, that we should also join in with Tehilla L’Dovid (universally called Ashrei), though this is not commonly practiced today.