Map - South Dublin County (South Dublin)

South Dublin (Átha Cliath Theas) is a county in Ireland, within the province of Leinster and the Eastern and Midland Region. It is one of three successor counties to County Dublin, which was disestablished for administrative purposes in 1994. South Dublin County Council is the local authority for the county. The county contains both dense suburbs of Dublin and stretches of unpopulated mountain. In 2016 it had a population of 278,767, making it the third most populous county in the state.

South Dublin has an area of 222.74 sqkm, making it the second-largest of the four local government areas in Dublin. It is bounded by Dublin City (15 km to the northeast), the River Liffey (separating it from Fingal to the north), Dún Laoghaire–Rathdown (to the east), County Kildare (to the west) and its hills adjoin the mountains of County Wicklow to the south.

The county town is Tallaght. Other important centres of population are Lucan and Clondalkin. Much of the county is heavily urbanised but small rural settlements exist in the southern and western parts. South Dublin had a population of 278,749 according to the 2016 census.