The Feast of the Immaculate Conception is a national holiday celebrated in Portugal on December 8, and it’s a significant event in the Catholic calendar. This day is particularly important in Portugal due to the country's deep Catholic roots. It is dedicated to the theological belief that the Virgin Mary, mother of Jesus, was conceived without Original Sin. This makes the holiday a joyous event, celebrating a concept that is one of the cornerstones of the Roman Catholic doctrine.

Throughout Portugal, the Feast of the Immaculate Conception is celebrated with religious processions and ceremonies. Specific traditions vary across the country's different regions but generally involve attending mass services. In many towns and villages, they have a tradition where children go door-to-door, reciting prayers or singing hymns dedicated to the Virgin Mary. In return, they are often given sweets or other small gifts.

The Feast of the Immaculate Conception is more than just a religious event in Portugal; it also marks the unofficial start of the Christmas season. Decorations begin to appear in homes and towns across the country, and the festive spirit starts to build in earnest. It's a time of reflection, celebration and preparation for the biggest religious event in the Christian calendar – Christmas.