The Government of Ireland Act 1920 will be 100 years old in December 2020. The act created the institutions for home rule in Ireland, including two devolved parliaments: one in the north and one in the south. Historian and member of the House of Lords Lord Lexden argues the act was a “vital staging post on the road” to the creation of the Irish Free State in 1922. This article reviews the system of government created by the 1920 act.