Ysgol Ardudwy is a bilingual secondary school for 11–16 year olds at Harlech, Gwynedd, Wales.

[1] It serves the seaside communities of Penrhyndeudraeth, Harlech, Abermaw (Barmouth) and nearby villages.

[3] The school was formerly led by headmaster Tudur Williams for 28 years until his abrupt resignation a week into a new school year in 2018.

However, one or two subjects are taught to some pupils in English or in both languages.

In December 2018, 34 per cent of pupils came from Welsh-speaking homes, but 89 per cent of the school's pupils were found to speak Welsh fluently.