Visakha Puja, or the Day of Vesak, is the festival celebrating the birth, enlightenment and parinirvana (passing away) of the Lord Buddha. It falls on the full moon day of the month of Visakha or Vesak, the sixth lunar month, (which usually falls during the period May in the Gregorian calendar).

According to the Theravada tradition, the three most important events in the life of the Buddha-his birth, his entry into enlightenment and his achievement of parinirvana-all occurred on the full moon day of Visakha. Aspects of the Dharma relating to the birth, enlightenment and parinirvana of the Buddha include gratitude, the Four Noble Truths and mindfulness

In Thailand, the Day of Vesak was first celebrated during the Sukhothai period (1249-1438 CE). It is believed to have been introduced from Sri Lanka where the festival, according to the Mahavamsa chronicle, was instituted around 2,100 years ago in the reign of King Dutthagamani, who instituted the celebration of Vesak day twenty-four times (Mahavesakhapuja ca catuvisati garayi). In the Sukhothai period, Thailand had a very close religious connection with Sri Lanka. Sri Lankan monks came to Sukhothai to propagate Buddhism and brought with them the practice of Visakha Puja, the Day of Vesak festival. The following is how the Nangnoppamat, a treatise on the tradition of Loi Krathong, describes the festival of the Day of Vesak:

"On Visakha Puja Day, the King, his officials of both the inner court and outer court, as well as the people of Sukhothai from every district and village cleaned and decorated the city of Sukhothai with flowers and incense, lighting the city with torches so that the whole city was bright and beautiful. The festival worshiping the Triple Gem continued three days and three nights. The King and royal family observed the precepts and performed many meritorious deeds. In the evening, the King and royal family, with the officials from both the inner and outer courts, went to the royal monastery to circumambulate the chief Buddha image. The people of Sukhothai encouraged each other to observe the precepts, listened to homilies, made offerings to individual monks and to the Sangha as a whole, offered meals to the monks and novices, and gave charity to the poor, the orphans, the helpless, the aged and the disabled. Some collected money to purchase animals of four legs and two legs, turtles and fish to preserve their lives by setting them free, in the belief that such actions would prolong their own lives".

Although no descriptions of Day of Vesak festivals have been found from the Ayutthaya (1350 -1767 CE), Thonburi (1767-1782 CE) or early Ratanakosin (Bangkok) periods, the royal chronicles record that King Rama II (1809-1824 CE), promoted a revival of the Day of Vesak festival throughout the kingdom, encouraging all his subjects to celebrate Visakha Puja by performing meritorious deeds as a way to prolong life, bring happiness and avoid suffering, sorrow, illness and unforeseen dangers. Thus the celebration of the Day of Vesak regained in Thailand its due prominence during the reign of King Rama II. The practice continues to the present day.

On the 13th December, 1999 at the General Assembly of the United Nations, Session No. 54, Agenda item 174, the representatives from Bangladesh, Bhutan, Cambodia, Chile, Cyprus, Grenada, Greece, Iceland, India, Indonesia, Ireland, Lao People's Democratic Republic, Lesotho, Maldives, Mauritius, Mongolia, Myanmar, Nepal, Nicaragua, Norway, Pakistan, Philippines, Portugal, Republic of Korea, Russian Federation, Seychelles, Slovakia, Spain, Sri Lanka, Suriname, Thailand, Turkey, Ukraine, and the United States of America proposed to the General Assembly that it recognize the Day of Vesak as an international day, and make appropriate arrangements for international observance of Vesak at United Nations Headquarters and at other United Nations offices.

The General Assembly of the United Nations took into consideration the fact that Buddhism is one of the world's oldest religions and that, for over two and a half millennia, it has made, and still continues to make, a significant contribution to human spirituality, and therefore resolved that appropriate arrangements be made for international observance of Vesak at United Nations Headquarters and at other United Nations offices. As a consequence, sixteen Buddhist countries jointly agreed to organize activities on the Day of Vesak at the United Nations Headquarters, New York, U.S.A. from 2000 onwards. Each country acted, in turn, as co-ordinator in organizing celebration of the Day of Vesak. Thailand was honoured to act as co-ordinator for celebration of the Day of Vesak at the United Nations Headquarters, New York, in 2004. Thailand, as the host country, subsequently invited more than 40 countries to jointly organize celebration of the Day of Vesak at the United Nations Regional Office for Asia and Pacific in 2005.

Gratitude is the principle that Buddhists should cultivate in their mind on the Day of Vesak to recollect the birth of the Buddha, who was born for the benefit of the many and out of compassion for the world.

Gratitude is appreciation of those who have done something for us. Acts of gratitude show how thankful we are for what we have received. One who initially does something for another is, in Pali, called pubbakari, "the first-doer". Pubbakaris include, for example, parents and teachers.

Children owe their parents gratitude for many things, for example, for bringing them into the world; for looking after them until they are grown up; for providing them with education, training and teaching them to refrain from that which is bad and establishing them in that which is good; for helping them to find suitable spouses and for giving them their inheritance. Grateful children, in turn, behave well, bring good a reputation to the family, look after their parents, help them with their work, and perform meritorious deeds in their memory once their parents have passed away.

Students should be grateful towards their teachers because their teachers impart knowledge to them, train and instruct them to be good citizens, teach the arts and sciences without exception, introduce them to other people and look after them. On their part, students, in appreciation of their teachers' kindness, study hard, honour them, show respect to them and do not forget their counsel.

Being grateful is a mark of being a good person. It is a positive contribution to the achievement of happiness in family and society. This is because the parents themselves fulfill their responsibility first; the children, in return, honour their own duty. The teacher first imparts knowledge of the arts and sciences and students, on their part, will repay the teacher by studying hard and showing respect. Apart from the relationships between parent and child, teacher and student, the good quality of gratitude can be employed between ruler and the ruled, employer and the employee, among friends and among all persons, thus encompassing all of humanity.

In Buddhism, the Buddha is the pubbakari, "the first-doer", in that he founded the Buddhist religion and showed the way to the end of suffering to those worthy of instruction. To show our gratitude, we make two kinds of offering: material and spiritual. The followers of the Buddha show their gratitude towards the Master by organizing Day of Vesak celebrations to promote Buddhism and by practicing the Dharma so that Buddhism will remain for many years to come.

The Four Noble Truths are the principles that the Buddhists should bear in mind on the Day of Vesak because it is the day upon which the Buddha realised those truths.

The Four Noble Truths constitute the highest truth, in that they do not change and are true for each and every one of us. They are: suffering, the cause of suffering, the cessation of suffering and the way to the cessation of suffering.

Suffering is the problem of life. The Buddha taught that suffering is intrinsic; it occurs in daily life and is common to all human beings. Intrinsic suffering includes the suffering of birth, old age and death. On a daily basis, it includes separation from loved ones, association with what one does not like and not having what one wants.

The cause of suffering is the root of the problem. The Buddha said that all suffering has its cause and that cause is tanha, desire and grasping.

The cessation of suffering: the problem of suffering can be resolved. According to the Buddha, all kinds of suffering can be eliminated by the elimination of tanha, that is, the eradication of desire.

The way to the cessation of suffering is the means of resolving the problem. The Buddha taught that solution to all life’s problems is the cessation of suffering, which can be achieved by following the Noble Eightfold Path with its threefold training in morality, concentration and wisdom.

Mindfulness is that part of the Dhamma that Buddhists should bear in mind on the Day of Vesak since, before he passed away, the Buddha gave his final instruction of Vayadhamma sankhara; appamadena sampadetha: “Subject to decay are all component things, work out your salvation with diligence”. So mindfulness is an important principle. All of the Buddha's teachings can be summarised under this mindfulness. Mindfulness means being careful in action, speech and thought. Mindfulness is the ability to be aware of thoughts, words and actions at the time that they occur. This means that in daily life one is constantly aware of one's movements through the four postures, namely walking, standing, sitting and lying down.

Mindfulness can be practiced in all the postures through constant attentiveness during standing, walking, sitting and lying down, and also when speaking, thinking or undertaking any other activity.

Mindfulness also means attentiveness. It means to always review the positive and negative aspects before doing, speaking or thinking anything. Mindfulness is the state of mind in which one knows at the present moment what one is doing, whilst attentiveness is the process of making a decision as to whether one should do this or that. So attentiveness helps to prevent a mind from falling into the power of the defilements.

To promote among Buddhists an awareness of the importance of the Day of Vesak and of the central teachings and practices related to it.

To help the Buddhists develop skillful thinking and wholesome deeds on the Day of Vesak and to help them in developing their own social and personal lives to practice the central teachings of gratitude, the Four Noble Truths and mindfulness.

To cultivate a positive attitude towards important days of the Buddhist calendar and to help men and women to see the value of living their life in accordance with the fundamental teachings of gratitude, the Four Noble Truths and mindfulness.

To imbue Buddhists with faith and a realisation of the importance of Buddhism.

To help Buddhists to become good Buddhists and to perform their religious duties correctly.

Clean the house; display the national flag and the Buddhist flag in the shrine area of the home and light candles to the Buddha.

Review the significance of the Day of Vesak, including the fundamental teachings of gratitude, the Four Noble Truths and mindfulness, applying them to the family culture.

As a family, perform meritorious deeds such as offering alms, giving charity and serving meals to the mother and father.

Practice the Dharma in the temple: pay respect to the monks, chant, listen to homilies, circumambulate, and meditate.

The elder members of the family should try to build a sense of friendship and care; the parents should lead by example in observing the Five Precepts and in promoting the five duties implied by them. Diligence, frugality, honesty and endurance should be encouraged.

The family should work together to discover the cause of any problems which have occurred and to find solutions from what they have learned.

Clean the school compound; hoist the national flag and the Buddhist flag; set up a shrine and light candles to the Buddha.

Teachers and students study together the importance of Visakha Puja with its fundamental teachings of gratitude, the Four Noble Truths and mindfulness applying them to the culture of the institution.

The teacher may have the students put up posters and banners, arrange an exhibition or essay competition, or an art show. Arrange a question and answer session on the Dhamma. Hold a presentation or initiate a dialog on Visakha Puja.

Honour the actions and behaviour of an exemplary student.

Take the students on field trips for participation in the public celebration of Day of Vesak at the temple, to make merit, offer alms, give charity, observe precepts, listen to homilies and discuss the Dhamma, to circumambulate, to meditate.

Encourage and help the teachers to give lessons promoting gratitude, the Four Noble Truths and mindfulness. Promote social research using the process of the Four Noble Truths.

Clean the office and its surroundings; display the national flag and the Buddhist flag; set up a shrine room and light candles to the Buddha.

Communicate the importance of Visakha Puja, together with the central teachings of gratitude, the Four Noble Truths and mindfulness applying them to the culture of workplace. Arrange for homilies and Dharma discussions. Offer charity for the public benefit, plant trees, donate blood. Employers and supervisors should permit employees to participate in volunteer work of their choice.

Publicly honour the actions and behaviour of an exemplary worker. Encourage any program which employs the Four Noble Truths to resolve problems and to advance the organization.

Clean the compound of the temple, society, foundation, department or organization; hoist the national flag and the Buddhist flag; set up a shrine and light candles to the Buddha.

The temple, society, club, department or organization should inform the public about Visakha Puja using all available media. Publicise the importance of Visakha Puja together with the central teachings of gratitude, the Four Noble Truths and mindfulness as a way of life as widely as possible among the people, locally and in such public places as airports, railway stations, bus stations, Dharma halls, markets and transportation depots. Invite the public to participate in activities involving Dharma practice and religious programs, such as making merit, giving alms, listening to homilies, observing precepts, paying respect to monks or chanting. Campaign through the mass media to reduce immorality and for the elimination of the sale of addictive drugs. Publicly honour exemplary organizations and individuals for their contributions to society. Campaign for the protection of environment, plant trees and clean public places. Arrange a competition of poems and articles; arrange a talk on Visakha Puja and recitations. Promote the value of a good citizen who benefits the society. Arrange programs to support the elderly, children, disabled, sick monks, prisoners and the socially disadvantaged.

Buddhists will come to understand the importance of Visakha Puja with its fundamental teachings of gratitude, the Four Noble Truths and mindfulness. Buddhists will come to develop a positive attitude towards Buddhism and to see the value of living a life in accordance with the central teachings of gratitude, the Four Noble Truths and mindfulness. Buddhists will come to be imbued with faith and to realise the importance of Buddhism. Buddhists will become good Buddhists who know correctly how to perform their religious duties.