Abhidhamma Day is a Theravada Buddhist tradition that is celebrated primarily in Myanmar. The event celebrates Gautama Buddha’s ascension into Tavatimsa heaven to teach his mother the Abhidhamma. The Abhidhamma Day is the day when Buddha returned to Earth after completing his delivery of Abhidhamma to his mother in Tavatimsa. The Abhidhamma Day falls on the full moon day of Thadingyut, the seventh month of the Burmese lunar calendar, which coincides with October in the Gregorian calendar.  The day is therefore sacred for the Buddhists.

Traditionally, Buddhists in Myanmar commemorate the day as Abhidhamma Day and hold annual Festival of Light of Thadingyut.  It is also known as the Buddha’s Mother Day.

Abhidhamma is the analytical doctrine of mental faculties and elements. The Abhidhamma Pitaka (or Abhidhamma scripture) contains the profound moral psychology and philosophy of Buddha’s teaching. In Abhidhamma, explanations are given on how and at which a person can create good or bad karmic thoughts according to his desires and other mental states. Abhidhamma teaches that the egoistic beliefs and other concepts such as ‘I’ and ‘you’, which we use in daily conversation, do not adequately describe the real nature of existence. The Abhidhamma explains the process of rebirth in various planes after the occurrence of death without anything to pass from one life to another.