Vassa also called Rains Retreat, is the traditional retreat during the rainy season lasting for three lunar months from July to October. During this time Buddhist monks remain in a single place, generally in their temples. In some monasteries, monks dedicate the Vassa to intensive meditation. During Vassa, many Buddhist lay people reinvigorate their spiritual training and adopt more ascetic practices, such as giving up meat, alcohol, or smoking (Vassa is sometimes known as "Buddhist Lent", though at least one prominent Theravada monk has objected to this usage- see ). And in countries such as Thailand, the laity will often take monastic vows for period of Vassa and return to lay life afterwards. Commonly, the number of years a monk has spent in monastic life is expressed by counting the number of Vassas he has observed.
The Vassa retreat has largely been given up by Mahayana Buddhists, as Mahayana Buddhism has typically flourished in regions without a rainy season, however for Mahayana schools such as Zen and Tibetan Buddhism other forms of retreat are common.