Baltinglass Abbey (Irish: Mainistir Bhealach Conglais)^[1] is a ruined medieval Cistercian abbey in Baltinglass, County Wicklow, Ireland. Founded by Diarmait Mac Murchada in 1148, the abbey was suppressed in 1536. It is today a National Monument.^[2]

Founded in 1148 by Diarmait Mac Murchada, the King of Leinster, Baltinglass Abbey sits beside the River Slaney in a valley of the Wicklow Mountains.^[3] The original name Belach Conglais means "pass of Cú Glas," referring to a mythological hero that was killed by wild boars.^[4] The abbey is roughly contemporary with Ferns Abbey, St Saviour's Priory, and possibly also Killeshin Church. ^[5]

Baltinglass Abbey was established as a daughter house of Mellifont Abbey, a Cistercian abbey near Drogheda.^[6] Diarmait gave it the Latin name Vallis Salutis, meaning "Valley of Salvation", and granted it eight parcels of land in the region as an endowment.

Grangecon, a nearby village, was originally an out-farm of the monks. They operated a corn-mill in the area that the village now occupies.^[7]

The first stage of the building was completed by 1170, it had become the mother house of Jerpoint Abbey in about 1160,^[8] and in 1228 it is recorded that there were 36 monks and 50 lay brothers living at Baltinglass.^[9]

The Abbey was occupied for nearly 400 years until it was shut down by the 1536 Dissolution of the Monasteries and granted to Edmond Butler, 3rd/13th Baron Dunboyne. A Church of Ireland church was built within the abbey itself in 1815, but it closed in 1883.^[10][11]

The stonework at the abbey shows carved humans and animals and is a particular Cistercian form of Romanesque architecture.^[12] The decoration on the capitals is similar to that at its daughter house Jerpoint.^{[13][14][15] [16]}

The surviving church (56 m in length) and some of the cloister date from the 12th century, consisting of the nave with aisles, chancel, square presbytery with three-light window and a pair of transepts from which small chapels project. The south aisle of the church is joined to the choir by a twelfth-century doorway. Part of the original cloister, to the south of the church, has been rebuilt. The church also has 13th and 15th-century additions. The east windows and tower were built in the nineteenth century.

A glazed tile potentially depicting Saint George and the Dragon was unearthed at the abbey in 1941. At that point, it was the only tile ever found in Ireland with a human figure painted on it.^[17]

• List of abbeys and priories in Ireland (County Wicklow)