Students at Ysgol Dewi Sant follow the National Curriculum for Wales.
At Key Stage 3 (Y7, Y8 and Y9) all students study English, Welsh, Mathematics, Science, Design & Technology, IT, Physical Education, Religious Education, Personal and Social Education (PSE), Art & Design, French, Geography, History and Music.
At Key Stage 4 (Y10 and Y11) the core of English, Welsh, Mathematics, Science, Physical Education, Religious Education & PSE is studied by all students. In addition, there is a choice of four option subjects.
In the sixth form a wide range of Advanced level and A/S level courses are offered together with some GCSE subjects.