National High School is a school in south Kolkata, in the state of West Bengal, India. It is one of the oldest schools in Kolkata. It is affiliated to the West Bengal Board of Secondary Education and the West Bengal Council of Higher Secondary Education.

The N R Iyer Memorial Education Society, Registered under Societies Registration Act, 1860 was formed by South Indian residents in Kolkata in January 1935 with the main object of taking over the Anglo-Tamil School founded in 1913 by the Tamil speaking people and promoting the cause of education primarily for the South Indian Children in Kolkata.

The Anglo-Tamil School was elevated to a High School in January 1938 and was named National High School. The Primary and Secondary sections were housed in the Society's own building at 164, Sarat Bose Road, Kolkata. Since the beginning, the Secondary Section was running as a co-educational school, but in 1960 it was bifurcated into two sections, one for boys and other for girls. The boys section moved to the Society's new building at 42/1, Hazra Road, Kolkata in 1964. The Kindergarten section was started in 1974, at 164, Sarat Bose Road, Kolkata. The Boys school has a Primary section attached to it since 1979. Higher Secondary Curriculum (Plus two course) was added to both the High School when the course was introduced by the Government. A Montessori Section was added in the year 1988 in the Boys School. Both the schools are managed by the N R Iyer Memorial Education Society.

High school is a term used in parts of the English-speaking world to describe institutions which provide all or part of secondary education, but not always the highest years of basic education, which can be called a "secondary school" or "secondary college" or other terms, depending on the nation or region (see below: Usage by country). The phrase "high school" is often incorporated into the name of the related institutions.

The term (as "high school") originated in Scotland, with the world's oldest being Edinburgh's Royal High School from 1505. The Royal High School was used as a model for the first public high school in the United States, the English High School founded in Boston, Massachusetts in 1821. The precise stage of schooling provided by a high school differs from country to country, and may vary within the same jurisdiction. In all of New Zealand and Malaysia along with parts of Australia, Bangladesh and Canada, high school is synonymous with secondary school, and encompasses the entire secondary stage of education.