A dominion was any one of several largely self-governing countries that remained, especially in the first half of the 20th century, under the British Crown as parts of the British Empire and then the British Commonwealth of Nations. The list of dominions as at 1926 included Australia, Canada, the Irish Free State, New Zealand, Newfoundland, and South Africa; later Ceylon (now Sri Lanka), India, and Pakistan also became dominions for short periods. Progressing from colonies, their degrees of colonial self-governance increased (and, in one case, decreased) but did so unevenly over the late 19th century through the 1930s. In the years following the Second World War, the British Empire was refashioned into the more modern (and more post-colonial) Commonwealth of Nations (after which the former dominions were often referred to as the Old Commonwealth). By the time this transition was formally finalised, in 1949, the old dominions had become more autonomous and independent nation states, each in their own right, either as a Commonwealth republic or a Commonwealth realm.
In 1925, the government of the United Kingdom created the Dominions Office from the Colonial Office, although for the next five years they shared the same secretary in charge of both offices. "Dominion status" was first accorded to Australia, Canada, the Irish Free State, New Zealand, Newfoundland, and South Africa at the 1926 Imperial Conference through the Balfour Declaration of 1926, recognising Great Britain and the Dominions as "autonomous communities within the British Empire, equal in status, in no way subordinate one to another in any aspect of their domestic or external affairs, though united by a common allegiance to the Crown and freely associated as members of the British Commonwealth of Nations". Their full legislative independence was subsequently confirmed in the Statute of Westminster 1931. In the 1920s and 1930s, they began to represent themselves in international bodies, in treaty making, and in foreign capitals. Vestiges of empire and colonial rule lasted in some dominions late into the 20th century and indeed still exist today.