Buddha's preaching of his First Sermon, the Dhammacakkappavattana Sutta, to the five ascetics took place at the ‘Deer Park', near Benares, on an Esala poya day thereby inaugurating his public ministry. The other noteworthy events connected with this day include the conception of the Bodhisatta in the womb of Queen Maya, his Great Renunciation, the performance of the Twin Miracle (yamaka-patihariya), and his preaching the Abhidhamma for the first time in the Tavatimsa heaven.

An additional factor that enhances the value of this poya to Sri Lanka is the first local ordination of a Sri Lankan, when Prince Arittha, the nephew of the king, entered the Order at Anuradhapura, under Arahant Mahinda, following the introduction of Buddhism. On this day there also took place the laying of the foundation for the celebrated dagoba, the Mahastupa or the Ruwanvelisaya and also its enshrinement of relics by King Dutugemunu. It is owing to the combination of all these events that the Sinhala Buddhists fittingly observe this day ceremonially by holding Esala festivals throughout the island, giving pride of place to the internationally famous Kandy Esala Perahera.

Esala poya assumes prominence for yet another ritual of the Sri Lankan Buddhists. This is the annual rains retreat of the monks, 'Vas', which commences on the day following the Esala full moon. On the next poya day, Nikini (August), those monks who failed to commence the normal Vas on the day following Esala Poya, are allowed to enter the 'late Vas'.