Mountain Ash Comprehensive School (Welsh: Ysgol Gyfun Aberpennar), known as MACS, is a comprehensive school near the town of Mountain Ash, Rhondda Cynon Taf, Wales. It is a mixed-sex school with approximately 950 pupils, including about 90 in the sixth form. The school was formerly known as Mountain Ash Grammar School (Welsh: Ysgol Ramadeg Aberpennar) and is located near the former .