Immaculate Conception, or 'Inmaculada Concepción' in Spanish, is a widely celebrated holiday in Chile. It is a Christian celebration that commemorates the belief that Mary, the mother of Jesus, was conceived without original sin, a doctrine of the Roman Catholic Church. This holiday falls on the 8th of December each year and is a public holiday throughout Chile.

On this day, many Chileans attend Mass at church to honor the Virgin Mary. In addition, one of the country's most cherished celebrations associated with the Immaculate Conception, is the 'Fiesta de la Purísima'. This event is particularly vibrant on the little island of Chiloé, where locals stage a joyous Virgen de la Andacollo festival, named after a statue of the virgin Mary, known to be very miraculous.

Apart from religious observances, the public holiday provides an opportunity for locals to spend time with family and friends. As it falls in the summer season, many families use this day off to kick off their summer vacation. With a deep-seated religious history and cultural significance, the Immaculate Conception remains one of the major holidays in the Chilean calendar.