Bealtaine was a Celtic feast which fell on 1 May (May Day). It marked the half-way point of the Celtic year. Bealtaine marked the beginning of a month-long celebration of sexual freedom in honor of the Great Mother and the Horned God. Trial marriages of a year and a day could be made at this time; if this proved unworkable, partners simply went their separate ways at the end of that time. Virginity was not prized among the Celts, since families were important to them. Sexual activity was encouraged, especially at Bealtaine. Green clothing was worn at this time of year, to honour the Earth Mother.

The opposite of Bealtaine in the Celtic calendar is Samhain.