Glascwm () is a community in the upper Edw valley in Radnorshire, Powys, Wales. The main settlement is concentrated in the two centrally located small villages of Frank's Bridge, located on the eastern slope of the valley, and Hundred House, located on the river terrace on the western side of the Edw. The remainder of the population lives in scattered farms and dwellings and in the three rural settlements of Cregrina, Glascwm, Bettws Diserth and Llansantffraed-in-Elwel. The surrounding area has extensive uninhabited uplands of moorland at Carneddau, Gilwern Hill, Gwaunceste Hill, Little Hill and Glascwm Hill. The A481 passes through the area.