The United Nations Association of Great Britain and Northern Ireland, more commonly known as UNA-UK, is the successor to the League of Nations Union (LNU).

UNA-UK held its first meeting in London on 7 June 1945. At that time delegates of 50 nations were meeting in San Francisco to finalise the United Nations Charter. Just as the League of Nations Union preceded the League, so the United Nations Association preceded the UN.

Work in the early months of the Association centered on re-establishing national and regional structures to support the new and revived LNU branches which were rapidly becoming active.

On 10 October 1945, UNA-UK filled the Royal Albert Hall in London for a national inaugural meeting. Interest in the Association grew rapidly.

By the time of UNA-UK’s annual meeting in 1951, 191 branches, 10 regional councils, the Council for Education in World Citizenship, the UN Student Association, national councils for Scotland and for Wales and 25 organisations affiliated at the national level were represented.