Most importantly, during his tenure Spanish was adopted as the official language of instruction in all levels of the Puerto Rico public education system, displacing instruction in English which had been pushed by the previous governments of Puerto Rico under US-appointed colonial governors.
[4] In 1946, the political leadership of the Popular Democratic Party recommended Villaronga for commissioner of Public Instruction, a post that at that time was appointed by the President of the United States.
[2] In 1948, however, Luis Muñoz Marín, the first popularly elected governor, named Mariano Villaronga Commissioner of Public Instruction.
In August 1949, Muñoz issued an executive order that all teaching would be done in Spanish at all levels in the public education system and that English would be offered as a special subject.
In 1952, when the Commonwealth of Puerto Rico was formed, Villaronga was designated secretary of Public Instruction, a position he held until 1957.