Today is Nikini Full Moon Poya Day.

The significant event that took place on Nikini Full Moon Poya Day was the holding of the first Sangha Council, led by Maha Kassapa.

Nikini Full Moon Poya Day is celebrated centering four important occurrences in Buddhist history.

Attainment of Arahatship by  Buddha’s chief attendant, Ananda Maha Thera, commencement of the first Dhamma Sangayana, convocation to settle the Buddhist canon and Pasu Vas or the commencement of the Vas period by those who had not started the period of sojourn on the Esala Full Moon Day, are some of them.

Buddhist monks commence Vas on Nikini Full Moon Day, in keeping with the enactment called Santhaha Karanaya. The circumstances which led to the enactment of  Santhaha Karanaya was the hardships caused to the bhikkhus due to rain.