The early inhabitants were people from neighboring towns and provinces who preferred to settle in this place because of its good agricultural prospects.

When the Spaniards came, the name Bulak was changed to Hacienda San Juan de Dios because 15,500 hectares of grazing and farming grounds were claimed by the friars.

Proceeds from the rentals were used to finance the operation of the San Juan de Dios Hospital in Manila.

As the population grew, a chapel was constructed under the parochial jurisdiction of San Rafael.

[6] During the Japanese occupation of the Philippines in 1942 the mansion Bahay na Pula of the Ilusorio family was confiscated by the Imperial Japanese Army and used as barracks and became a place where local so-called comfort women were forced to work.

Poverty Incidence of San Ildefonso Source: Philippine Statistics Authority[13][14][15][16][17][18][19][20]