Simbang Gabi lasts for nine consecutive days beginning December 16. Traditionally, it is held at dawn, but some parishes offer anticipated masses one night in advance. This religious event dates back to the time when Miguel Lopez de Legazpi celebrated the first feast of the Nativity in 1565 in the archipelago.

Simbang Gabi traces its roots in Mexico when, in 1587, Fray Diego de Soria, friar of the convent of San Agustin Acolman, petitioned the Pope for permission to hold Christmastide masses outdoors because the church could not accommodate the multitude that attended the dawn services. When the request was granted, the masses became known as Misa de Aguinaldo.

It was in the 16th century when Pope Sixtus V decreed that these pre-dawn masses be also held in the Philippines starting every December 16. The decree was in keeping with the nine-day traditional festivals of Filipinos in celebrating auspicious occasions like harvest time. It was also meant to give farmers a chance to hear mass before setting out for the fields. Rural Filipinos were used to starting the day two hours before sunrise.

Church bells resound to call the faithful to Simbang Gabi. In some provinces, brass bands play traditional Christmas music and parish priests would go as far as knocking on the doors of every home. After the nine-day Simbang Gabi, follows the Misa de Gallo (Mass of the Rooster). This is held midnight of December 24 to welcome the birth of the Savior. In some churches, the panunuluyan, depicting Mary and Joseph's efforts to find a suitable birthplace, is reenacted and the baby Jesus first makes his appearance in the manger of the Belen, the Nativity Scene.