The Monlam Chenmo, also known as The Great Prayer Festival, is the most important Tibetan Buddhist celebration of the year and begins on the 4th day of the 1st Tibetan Lunar month. It was established in Lhasa in 1409 by Tsongkhapa, the great philosopher and founder of the Gelug tradition of Tibetan Buddhism.The aim of the Great Prayer Festival was, by bringing together the largest possible congregations of monks, scholars and holy beings, to spread the air with powerful blessings, clear it of negativities and bring in good tidings. The Festival included many events and was for all a time of excitement and renewal.The Festival lasted 21 days and more than 20,000 monks from the three great monasteries, the two Tantric Colleges, Meru, Shede, Gonkhar Chöde, Ratö and six other monasteries all participated. The event took place in Lhasa’s main temple the Tsuklhakhang. and attracted throngs of people from as far as Kham and Amdo, who came to make offerings and receive blessings from the huge congregation of monks.  At the first Monlam, Tsongkhapa offered a jewel crown to Jowo Rinpoche, the famed Buddha image brought to Tibet in the 8th century by the Chinese princess Wan Chen when she came to marry King Songtsen Gampo. During the Festival, the running of the city of Lhasa was turned over to Drepung Monastery and they became in charge law and order and the resolving any disputes. For scholars, the highlights of the Festival were the debates where the Sixteen Lharampa Geshes who were eligible to pass their examinations that year took their finals in the form of a public debate. Other events included the Ganden Tri Rinpoche, head of the Gelukpa Tradition, giving a discourse on the Buddha's deeds, the Butter Sculpture competition and the Maitreya Buddhist procession.  

The Butter Sculpture competition took place on the fifteenth day of the new lunar year. Monks of all the different colleges of Drepung, Sera and Ganden, the two Tantric Colleges, several small monasteries in Lhasa, and a number of prominent aristocratic families competed to make extensive, elaborate and detailed sculptures in the form of large medallions depicting religious themes, flowers and mythical creatures, entirely of colored butter. Fixed on a rigid base of wood and leather, they could be as high as three stories and were exhibited along the Bakhor, in the area near the Tsuklhakhang. The viewing and judging took place at night.The Maitreya Precession took place on the twenty‑third of the month. The sacred statue of Maitreya Buddha was carried in procession through the streets of Lhasa amidst great festivity. People crowded around the procession, seeking the statue's blessing, looking forward to the age of Maitreya when everyone would be mindful of ethics, sincere, honest and free from sickness and distress.

Today, the most important Monlam Festival takes place at Labrang Tashikyil Monastery, where over 3000 monks assemble and celebrate all the above described events.