The engagement ceremony is called Nichayathartham or Poo Vaithal. The Nadar engagement ritual is the first pre-marriage event conducted and holds a lot of significance. It is conducted after the families have met and the prospective bride and groom meet to confirm that they like each other. This ceremony acts as a confirmation of the marriage and the marriage date is agreed upon during this ceremony. 

What Happens During the Nichayathartham in Tamil Nadar Weddings
Maternal uncles of both bride and groom play an important role in Tamil Hindu weddings and the same is true in the Nadar community too. The marriage is confirmed by agreeing upon the venue and date. After confirmation, the uncles exchange garlands and apply sandal paste on their forehead and forearms. Both families also bring salt and turmeric which is exchanged by the uncles.

The bride is then presented with a Nichayadartha Pattu which is silk saree from the groom's side. Groom's sister brings the saree and helps the bride to drape the saree. She then places flowers on the bride's hair and garlands her. The elders of the family also bless the bride. 

The Poo Vaithal or placing flowers on the bride's head is an important event in this ritual, it is significant as it shows that the mother-in-law has accepted her as a bride and a new member of her family. It also gives a chance to the bride to express her approval or disapproval of this union. If the bride allows the groom's mother to keep strands of flowers on her hair it shows that she accepts this wedding.