On January 1967, San Isidro Catholic School was born with its humble beginnings: the first group of about 20 boys and girls aged four to eight attended their first class in the old social hall building, a structure that looks like a gym. With Religion as the major subject, the school did not charge tuition. Mrs. Ma. Luisa C. Sevilla offered her services as Principal of the school while Miss Edelisa L. Daco as the only teacher
With high hopes, the school continued to grow. By 1969, the school was offering Nursery, Kindergarten, Preparatory, and Grade One.
After Ledesma's presidency, his yearning for building construction did not change. He continued soliciting funds and later on, the stock market boomed and the value of the school's investments augmented.
Years after, the school was offering education in all elementary levels. On February 6, 1967, Msgr. Clemente Lopez took over the San Isidro Parish and assumed the role as School Director. To accomodate the increasing number of students, an annex building was constructed on March 1988 and was inaugurated and blessed by the late, His Eminence Jaime L. Cardinal Sin on July 17, 1989