The Ruabon Grammar School was situated in Ruabon, Denbighshire in north-east Wales. It provided a grammar school education to boys in the parishes of Ruabon and Erbistock. Ruabon Grammar School for Boys became a Denbighshire County secondary school in 1894 and new buildings, including classrooms and laboratories were added in 1896, with further major building works taking place in the 1920s and 1940s.