This school's beginnings lie in three different schools;
The National School for Girls Lady Methuen's School for Girls Corsham British School (for boys)
Lady Methuen's School was founded in about 1816 while the National School probably started in the 1840s. By 1858 they had been combined with 70 pupils - 40 paying school fees of one old penny a week and 30 being educated for free as Lady Methuen's scholars. They were taught by one schoolmistress in two rooms that had been made into one large room, with a floor of part flagstones and part wooden boards, with desks fixed around the walls. In 1858 there were 85 boys in the British School being taught by one qualified schoolmaster and two pupil teachers. It was described as 'A decidedly successful rural school. Discipline and organization, though not faultless, superior to the average in the district. Mr Neate [the schoolmaster] has, besides, exercised his pupils in an intelligent form of mental drill.' The British School was probably built around 1840 as it received a grant of money in that year.
In 1893 a School Board for Corsham was formed and became responsible for both the Methuen School (girls) and the British School (boys), as well as the schools at Pickwick and Neston. In 1894-5 the Board acquired land adjoining the British School and put up new buildings at a cost of £3,640. In 1895 all the buildings on this site were used to provide separate schools for the infants and the boys. At this time there were 124 girls at the Methuen School, and 284 boys and infants at Board School, formerly the British School.
In 1903 the duties of the Corsham School Board were taken over by Wiltshire County Council who then became responsible for all of the schools in Corsham. The school at Pickwick closed in 1922 and the girls were transferred to the Methuen School and the boys to what was now the Corsham County School. In 1923 the girls' and boys' schools were merged and the girls joined the boys on the County School site. With 300 pupils this now became the Corsham County Junior School and the infants were moved into the old Methuen School as the Corsham County Infants' School. Some of the rooms in the old British School buildings were adapted for woodwork and housecraft lessons.
As the population of Corsham increased there were too many children for the accommodation available at the school and in 1943 Corsham Regis School opened and took a large number of the local children. Despite this two more classrooms had to be built at the County School in 1953. Until 1955 the schools in Corsham were elementary (all age) schools, which meant that from 1947 children up to the age of 15 were taught in them. From 1918 to 1947 the school leaving age had been 14. In 1955 the Corsham Secondary School opened and 363 boys and girls aged 11 to 15 were transferred there from the other schools. There were then 258 children remaining at the County Junior School in Station Road. In 1994 the school moved into new buildings at Pound Pill and there were 292 children on the register in that year. The school has expanded greatly since then and in September 2005 there were 417 children at the school.