Ballaghaderreen is a town in County Roscommon, Ireland. It was part of County Mayo prior to 1898. It is in the north-west of the county, near the borders with counties Mayo and Sligo, just off the N5 road. The population was 1,808 in the 2016 census.

County Roscommon is a county in Ireland. It is part of the province of Connacht and the Northern and Western Region. It is the 11th largest Irish county by area and 26th most populous. Its county town and largest town is Roscommon. Roscommon County Council is the local authority for the county. The population of the county was 69,995 as of the 2022 census.