Amman Valley Intermediate School was established in 1914 in temporary premises of a converted public laundry building. It was initially not known what subjects would be taken at the new Intermediate School; the Board of Education believing pupils requiring technical education were should be taught at Amman Valley due to an industrial catchment area where coalmining and tinplate manufacturing was prominent, whereas those requiring Classical education were to be taught at Llandeilo. The Amman Valley Intermediate School opened its doors on 29 September 1914 with accommodation for 186 boys and girls and 156 enrolled in the first term. The curriculum had a technical bias. Chief Inspector of Schools, Owen M. Edwards noted on his visit on 9 December 1914: 'Buildings: They are much better than anything I expected to find. They consist of (a) old converted laundry: this is the main room, consisting of 7 classrooms, Headmaster's Room, Mistresses' Room, Masters' Room, Store Room. (b) new temporary buildings (zinc and wood) - Bloc I: Spacious kitchen and Manual Work Room (the latter is used as an Assembly Room); Block II: Laboratories: a Chemistry b Physics and Botany; Block III: Boys' Offices (Bucket system: septic tank for urinals); Block IV: Girls' Offices.'

New permanent buildings were built in 1926-8 on Margaret Street, designed by the architect W. Vincent, with pupils moving in on 23 January 1928. The building is 2-3 storied, stone-built with lighter stone window and gable surrounds. The school later became Amman Valley Grammar and Amman Valley Comprehensive.  Extensions were added in the 1960's and in 2014 further extensions and refurbishment work was carried out under the 21st Century Schools Programme which included a new 6th form common room, library, staff workrooms, science laboratories, and a reception area. Three new sports fields, a cricket pitch, changing rooms and shower facilities were also installed.

Sources: early black and white postcard, undated; 'The Welsh Department of the Board of Education and the establishment of a Carmarthenshire intermediate school': (Wynford Davies, Journal for the National Library of Wales, Vol 20, 1977/78, pp.131-150; 'Ysgol Dyffryn Aman, Carmarthenshire County Council Project Overview'

RCAHMW, 8th January 2008. Updated by M. Powel, RCAHMW, July 2022.