Within Thai Buddhism, Uposatha unfolds as a rhythm of renewal tied to the lunar cycle, occurring on the new moon, full moon, and the quarter-moon days. These days draw both monastics and laypeople to the temple, where the emphasis falls on merit, moral purification, and the strengthening of the relationship with the sangha. Lay Buddhists commonly arrive at the wat early in the morning to offer food to the monks, together with flowers, candles, and incense, and to make donations that support the temple and its community activities. Such offerings are not merely ritual gestures; they are understood as concrete expressions of generosity and reverence that help shape a wholesome mind.

A central feature of lay observance is the deliberate tightening of ethical discipline. Many practitioners use these days to keep the Five Precepts more carefully, while a significant number adopt the Eight Precepts, adding celibacy, simplicity in eating, and the renunciation of entertainment and adornment. This temporary embrace of stricter conduct functions as a kind of moral retreat, allowing everyday life to be reoriented around restraint, mindfulness, and clarity. Abstaining from intoxicants and frivolous activities, and often from sexual activity, creates the inner space in which the teachings can be more deeply heard and contemplated.

The temple on Uposatha becomes a place of shared listening and stillness. Monks offer Dhamma talks, recite scriptures, and lead chanting, while laypeople join in recitation and meditation. Some remain at the temple for much of the day, or even overnight, engaging in extended practice that blends devotion, reflection, and silence. These communal gatherings, where families and neighbors assemble, naturally strengthen social bonds and transmit Buddhist values across generations, so that ethical and contemplative ideals are woven into the fabric of everyday communal life.

For the monastic community, Uposatha carries an additional, distinctly formal dimension. Fully ordained monks assemble to recite the Pātimokkha, the code of monastic rules, and to confess minor offenses beforehand. This shared act of confession and recitation serves as a regular purification of the sangha, reaffirming its commitment to the Vinaya and restoring harmony where it may have frayed. In this way, Uposatha functions simultaneously as a lay festival of merit-making and moral renewal, and as a disciplined monastic convocation dedicated to maintaining the integrity and purity of the communal life.