The constituency consisted of the two neighbouring towns of Aberdare and Mountain Ash in Glamorgan, Wales.
Under the Representation of the People Act 1918, the existing parliamentary borough of Merthyr Tydfil was divided into two single-member constituencies.
The first member for Aberdare was Charles Stanton, Stanton was a militant miners' agent in the pre-1914 era but had become an equally fierce proponent of the war effort which brought him into conflict with former colleagues including Keir Hardie.
By 1922, Stanton's appeal and popularity had faded and he was defeated by George Hall, who held the seat for over twenty years.
Labour's hold on Aberdare was never threatened thereafter although Plaid Cymru did make a strong showing at the 1970 general election.