An excerpt from an article written by Reid Davis Esmabe and published in Skylark, the official publication of San Isidro National High School some time in SY 2005-2006, this timeline (in reverse chronological order) shows the list of Principals of SINHS and a short information about their achievement or contribution in improving the school.
2004 - Mr. Venancio C. Pimentel, Principal II, replaced Mrs. Esmabe (Oct. 18, 2004).
1994- 2004 - Mrs. Emily B. Esmabe replaced Mrs. Oriño and attended to more improvement of the school's physical facilities. The school was renamned San Isidro National High School.
1984-1994 - Mrs. Gloria A. Oriño was the new administrator who, by DECS Order # 41 s. 1998, worked on adopting the name San Isidro Nationalized High School.
1981 - Mrs. Elizabeth P. Palo took the helm as the first Secondary School Principal I of the school.
1976 - Mr. Jaime Orcine took over as Asst. Principal
1975 - There was an increase in student population. Mr. Faustino E. Galvo was the Asst. Principal.
1972- 1974 - San Isidro Barrio high School changed its name to San Isidro Barangay High School (DECS Order # 46 s. 74) with Asst. Principal Mr. Jaime B. Villamora.
1970- 1971 - Some school buildings were built under the administration of Mrs. Encarnacion R. Aguja, Asst. Principal.
1965 - Mr. Jovito M. Palo Sr. established San Isidro Barrio High School with the help of parents and Barangay Council, with him as Asst. Principal.