It was established on 14 February 1975 by Elizabeth II, Queen of Australia, to recognise Australian citizens and other persons for achievement, meritorious service, or for both.
In general, recipients who are not Australian citizens are appointed honorary companions, though there have been certain exceptions.
(For example, Prince Philip's appointment as AC (mil.)
[1]) Seven companions have later been promoted to knight or dame of the Order of Australia: Sir John Kerr, Sir Gordon Jackson, Dame Quentin Bryce, Sir Peter Cosgrove, Dame Marie Bashir, Sir Angus Houston and Prince Philip, Duke of Edinburgh.
[63] A list of links to announcements of all awards appears on the Governor-General's website.