Dalle de verre, sometimes simply called slab glass, is an architectural glazing approach in which thick slabs (dalles) of coloured glass are embedded in concrete or resin and arranged to form patterns. In Ireland several architects championed this new material and incorporated walls of dalle de verre in their churches from the 1960s. Though a pivotal stylistic change for Irish ecclesiastical glass, little has been written about this unique technique. This article will highlight some of the fine examples of dalle de verre which can be found in Ireland. It will discuss how the inherent qualities of dalle de verre lent itself to the modernist aesthetic of the era, allowing architects to embrace innovative techniques of construction and to cast off traditional stained glass conventions in favour of whole walls of colour. It will also touch on the decline of dalle de verre as an architectural medium.