The Government of Ireland Act 1920 (10 & 11 Geo. 5 c. 67) was the Act

Act of Parliament

An Act of Parliament is a statute enacted as primary legislation by a national or sub-national parliament. In the Republic of Ireland the term Act of the Oireachtas is used, and in the United States the term Act of Congress is used.In Commonwealth countries, the term is used both in a narrow...

 of the Parliament of the United Kingdom

Parliament of the United Kingdom

The Parliament of the United Kingdom of Great Britain and Northern Ireland is the supreme legislative body in the United Kingdom, British Crown dependencies and British overseas territories, located in London...

 which partitioned Ireland

Partition of Ireland

The partition of Ireland was the division of the island of Ireland into two distinct territories, now Northern Ireland and the Republic of Ireland . Partition occurred when the British Parliament passed the Government of Ireland Act 1920...

. The Act's long title

Long title

The long title is the formal title appearing at the head of a statute or other legislative instrument...

 was "An Act to provide for the better government of Ireland"; it is also known as the Fourth Home Rule Bill or (less accurately) as the Fourth Home Rule Act.

The Act was intended to establish separate Home Rule

Home rule

Home rule is the power of a constituent part of a state to exercise such of the state's powers of governance within its own administrative area that have been devolved to it by the central government....

 institutions within two new subdivisions of Ireland

Ireland

Ireland is an island to the northwest of continental Europe. It is the third-largest island in Europe and the twentieth-largest island on Earth...

: the six north-eastern counties were to form "Northern Ireland

Northern Ireland

Northern Ireland is one of the four countries of the United Kingdom. Situated in the north-east of the island of Ireland, it shares a border with the Republic of Ireland to the south and west...

", while the larger part of the country was to form "Southern Ireland

Southern Ireland

Southern Ireland was a short-lived autonomous region of the United Kingdom established on 3 May 1921 and dissolved on 6 December 1922.Southern Ireland was established under the Government of Ireland Act 1920 together with its sister region, Northern Ireland...

".