Vassāvāsa, also known as the Rains Retreat, is a three-month period during the rainy season when monks reside in one monastery to focus deeply on study, meditation, and Dhamma practice. At Ehipassiko Buddhist Monastery, this retreat is observed with dedication and discipline, usually beginning on the full moon of Ashadh (June–July) and ending on the full moon of Ashwin/Kartik (October).

During this time, monks engage in intensive spiritual training, teaching, and community service, while lay devotees support them by offering food, robes, and other necessities. Vassāvāsa helps strengthen the Sangha, preserve monastic discipline, and inspire the community to live mindfully and compassionately.