County Roscommon is a county in the western region of the Republic of Ireland. It is also part of the province of Connacht. It is the 11th largest Irish county by area and 27th 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 is 64,065 according to the 2011 census. It is the third largest of Connacht’s five counties by size and fourth largest in terms of population.