Ysgol Dyffryn Teifi was a bilingual (Welsh and English) comprehensive school in Llandysul, Ceredigion. It stood on the site of the previous Llandysul Grammar School. The school was established in 1984 following the re-organisation of education in the Teifi Valley.^[1] It was formerly a county school and grammar school dating back to the 19th century.

In 2001 there were 570 pupils at the school,^[1] the numbers then dropped, but had increased once more to 527 in 2007, and were expected to continue to gradually increase.^[2] 78% of the pupils were from homes where Welsh was the main language spoken in 2001,^[1] this increased to 83% in 2007, with 91% of the pupils able to speak the language to first language standard.^[2]

Ysgol Dyffryn Teifi amalgamated with Aberbanc, Coed y Bryn, Pontsian and Llandysul primary schools in September 2016 to become Wales’ first purpose built combined primary and secondary Welsh-medium community school, Ysgol Bro Teifi.^[3]

Former Ysgol Dyffryn Teifi pupils of note include:

• Kay Swinburne, Conservative Member of the European Parliament for Wales
• Paul Davies, Conservative Member of the Welsh Assembly for Preseli Pembrokeshire
• T. Llew Jones, Welsh language children's books author
• Emyr Llewelyn, Welsh political activist
• Evan James Williams (1903-1945), physicist
• Evan Tom Davies (1904-1973), mathematician and linguist
• Sioned James (1974-2016)
• John Bowen Jones [cy]
• Aled Hall, Welsh classical tenor and opera artist.
• Cate le Bon, Musician and producer

• Official school website
• Atgofion Ysgol Ramadeg Dyffryn Teifi - David Milwyn Evans, BBC Cymru

52°02′28″N 4°18′58″W / 52.041°N 4.316°W / 52.041; -4.316