St. Assam's is the name of two historic churches in the village of Raheny, Dublin, one a ruin in the middle of the village, one the structurally sound but no longer primary church built for the local Roman Catholic community of the area after the revival of religious rights. Both buildings lie within the area of the ráth (ring fort) which gave the village and district its name, and which was perhaps 110 m across.

This article includes a list of general references, but it lacks sufficient corresponding inline citations. (February 2022)

There was settlement in the Raheny area dating back to at least Celtic times, and it is believed a Christian establishment back to early Christian times in Ireland. The Parish of Raheny was erected in the 12th century, not later than 1152, probably initially in the Archdiocese of Glendalough and then in the Fingal Deanery of the Diocese of Dublin, and almost certainly had had a church for many years by then.

The first surviving reference to a church building in the area dates from 1189, in a papal bull of Clement. The Chapel of Raheny is mentioned again in a concession of the Archbishop of Dublin (1372) and a will (John Sheriff, 1472), which left money "for the care of the churches of Raheny, Coolock and Little Grange.^[1]" No specific church name is given in any of these documents.

From a reference in the Parliamentary Gazetteer to 1609, the older of the current churches may have been standing in some form. Whatever building was there, the regal visitation report of 1615 for north County Dublin references it, with repairs due to the chancel. By this period of the early 17th century, the church was almost certainly operating within the established church, the Church of Ireland, albeit most of the population were Catholic, probably worshipping in houses, or perhaps at Coolock or Artaine (see Parish of Coolock (Roman Catholic).

The now-ruined Church of St. Assam, locally known as "the old Protestant church", was rebuilt in 1712 on the site of "the parochial church dedicated to St. Assam", according to a dedication stone in the wall. It was a simple structure, 16.25 m by 7.15 m externally (with walls 0.75 m thick), and a mid-19th century plan shows a porch at the west end and a vestry at the east end of the north side, with internal arrangements for 116 worshippers. The porch is described in the Parliamentary Gazetteer as having a flat bell turret while the still-high east gable had a large window with tracery. Rectangular sockets on the walls may have been used to hold wooden panelling prior to the closure of the church in 1889, following the building of All Saints Church a few hundred metres citywards.

The church is surrounded by a walled graveyard, long closed to burials, beyond one wall of which is one of Raheny's three old schoolhouses.

The church was kept in order for some time after closure but represented a considerable burden on the small Church of Ireland Parish of Raheny and was eventually partially dismantled, most notably in 1920. Later still, in 1976, church and graveyard were transferred to the care of Dublin Corporation.

Following years of restrictions, Roman Catholics gradually began to rebuild parochial structures and church facilities across Ireland from the early-mid 19th century. The historic Parish of Raheny had been merged into a union parish, based initially around Coolock, and later Clontarf, and this began to be broken up in the mid-18th century. As part of this process, it was decided to restore Catholic public worship in Raheny (most locals worshipped at Coolock, and some perhaps at Clontarf), and land was secured at the top of Main Street, running towards the Santry River. Subscriptions were collected, and as was common in that period, came from people of various denominations.

A design was commissioned by the well-known architect Patrick Byrne, who also worked on a number of other churches, and the first stone was laid in 1859. The church was officially opened in 1864 by the Catholic Archbishop of Dublin, Dr. Cullen, with a gala reception at a local "big house", Raheny Park, afterwards.

The church was built in the Gothic style, with a small belfry at one end, and a range of stained glass in the windows. It has a door at the north east, leading to a porch, then a small lobby, with a meeting room to the left and the nave to the right.

St. Assam's, initially one of several churches in larger parochial structures, became Parish Church of Raheny when that area resumed its independent existence and served the fast-growing Parish of Raheny

An engraved Celtic cross stands next to the church in memory of Marie Elizabeth Hayes, an influential medical missionary who grew up in Raheny and served as a member of the Cambridge Mission to Delhi.

The newer St. Assam's is listed as a protected structure under the Dublin City Development Plan.^{[citation needed]}

• Garrett, Arthur (1990). Through Countless Ages: The Story of the Church and Parish of All Saints, and the District of Raheny. Raheny, Dublin.{{cite book}}: CS1 maint: location missing publisher (link)