While there is no officially defined boundary, it is surrounded by the areas of Sallynoggin, Dalkey, Dún Laoghaire, Glasthule and Johnstown. The Church of Ireland does have a defined boundary for the Parish of Glenageary.
On early 20th century maps Glenageary and Sallynoggin are considered to be the same place and it wasn't until the building of local authority houses in the late 1940s and 1950s in the townlands of Honeypark and Thomastown by Dún Laoghaire Borough Corporation that a clear distinction between Sallynoggin and Glenageary was created.
The Roman Catholic Parish of Sallynoggin/Glenageary covers all of Sallynoggin, Rochestown and much of Upper Glenageary.
Glenageary is a quiet suburb and consists mostly of private dwellings with shops and some amenities in places.
Until the late 1940s, Glenageary, like much of the south County Dublin, consisted mostly of large manor estates - each comprising a large house, some woodland and cultivated or landscaped fields. Since then it has been extensively redeveloped. Most of the original manors have been demolished and low density housing developments built.
Glenageary has one church, St Paul's at the junction of Adelaide and Silchester Roads, which is a (Church of Ireland) church. It was opened in 1868.
- Sinéad O'Connor and her novelist brother Joseph O'Connor spent some of their early lives in Glenageary.
- The former Church of Ireland Archdeacon of Dublin, was rector of St Pauls, Glenageary for twenty-four years and a local resident. Previous rectors have also been similarly promoted – to bishop; John Duggan (Tuam) and Noel Willoughby (Cashel & Ossory) and to archbishop; Dr. Walton Empey (Dublin); Jamie Noble (Castlebarr)
- Niall Connolly, one of the Colombia Three spent his childhood in Glenageary
- Colm Ó Cíosóig, musician and drummer of My Bloody Valentine, is from Glenageary.
- A 17 year old resident, Raonaid Murray, was murdered on Silchester Road on 4 September 1999 near her home.
The area is served by Dublin Bus, including routes 7, 8, 45A, 59, and 111 although these vary in frequency and service periods. Glenageary has its own railway station which is served by Iarnród Éireann's DART that provides a service between Greystones to the south, and Howth and Malahide to the north. Glenageary railway station opened on 1 November 1867.
- "Glenageary station". Railscot – Irish Railways. Retrieved 2007-09-02.
- Dún Laoghaire-Rathdown County Council
- St Paul's Church, Glenageary
- Glenageary/Killiney National School
- Dalkey School Project National School
- Rathdown Secondary School
- Glenageary Lawn Tennis Club