The history of Australia since 1945 has seen long periods of economic prosperity and the introduction of an expanded and multi-ethnic immigration program, which has coincided with moves away from Britain in political, social and cultural terms and towards increasing engagement with the United States and Asia.

End of the 1940s

In 1944, the Liberal Party of Australia was formed, with Robert Menzies as its founding leader. The party would come to dominate the early decades of the post-war period. Outlining his vision for a new political movement in 1944, Menzies said:

In April 1945, Prime Minister John Curtin despatched an Australian delegation which included attorney-general and minister for external affairs H. V. Evatt to discuss formation of the United Nations. Australia played a significant mediatory role in these early years of the United Nations, successfully lobbying for an increased role for smaller and middle-ranking nations and a stronger commitment to employment rights into the U.N. Charter. Evatt was elected president of the third session of the United Nations General Assembly (September 1948 to May 1949).

When Labor Prime Minister John Curtin died in July 1945, Frank Forde served as prime minister from 6–13 July, before the party elected Ben Chifley as Curtin's successor. Chifley, a former railway engine driver, won the 1946 election. His government introduced national projects, including the Snowy Mountains Scheme and an assisted immigration program and pursued centralist economic policies – making the Commonwealth the collector of income tax, and seeking to nationalise the private banks. At the conference of the New South Wales Labor Party in June 1949, Chifely sought to define the labour movement as having:

With an increasingly uncertain economic outlook, after his attempt to nationalise the banks and the coal strike by the Communist-dominated Miners Federation, Chifley lost office at the 1949 federal election to Menzies' newly established Liberal Party, in coalition with the Country Party.

Immigration and the post-war boom

After World War II, Australia launched a massive immigration program, believing that having narrowly avoided a Japanese invasion, Australia must "populate or perish." As Prime Minister Ben Chifley would later declare, "a powerful enemy looked hungrily toward Australia. In tomorrow's gun flash that threat could come again. We must populate Australia as rapidly as we can before someone else decides to populate it for us." Hundreds of thousands of displaced Europeans, including for the first time large numbers of Jews, migrated to Australia. More than two million people immigrated to Australia from Europe during the 20 years after the end of the war.

From the outset, it was intended that the bulk of these immigrants should be mainly from the British Isles, and that the post-war immigration scheme would preserve the British character of Australian society. Although Great Britain remained the predominant source of immigrants, the pool of source countries was expanded to include Continental European countries in order to meet Australia's ambitious immigration targets. From the late 1940s onwards, Australia received significant waves of people from countries such as Greece, Italy, Malta, Germany, Yugoslavia and the Netherlands. Australia actively sought these immigrants, with the government assisting many of them and they found work due to an expanding economy and major infrastructure projects.

The Australian economy stood in sharp contrast to war-ravaged Europe, and newly arrived migrants found employment in a booming manufacturing industry and government assisted programs such as the Snowy Mountains Scheme. This hydroelectricity and irrigation complex in south-east Australia consisted of sixteen major dams and seven power stations constructed between 1949 and 1974. It remains the largest engineering project undertaken in Australia. Necessitating the employment of 100,000 people from over 30 countries, to many it denotes the birth of multicultural Australia.

In 1949 the 1941–1949 Labor government (led by Ben Chifley after John Curtin's death in 1945) was defeated by a Liberal–National Party Coalition government headed by Menzies. Politically, the Menzies government and the Liberal Party of Australia dominated much of the immediate post-war era, defeating the Chifley government in 1949, in part over a Labor proposal to nationalise banksJan Bassett (1986) p.18 and following a crippling coal strike influenced by the Australian Communist Party. Menzies became the country's longest-serving prime minister and the Liberal party, in coalition with the rural based Country Party, won every federal election until 1972.

As in the United States in the early 1950s, allegations of communist influence in society saw tensions emerge in politics. Refugees from Soviet dominated Eastern Europe immigrated to Australia, while to Australia's north, Mao Zedong won the Chinese Civil War in 1949 and in June 1950, Communist North Korea invaded South Korea. The Menzies government responded to a United States led United Nations Security Council request for military aid for South Korea and diverted forces from occupied Japan to begin Australia's involvement in the Korean War. After fighting to a bitter standstill, the UN and North Korea signed a ceasefire agreement in July 1953. Australian forces had participated in such major battles as Kapyong and Maryang San. Seventeen thousand Australians had served and casualties amounted to more than 1,500, of whom 339 were killed.

During the course of the Korean War, the Menzies government attempted to ban the Communist Party of Australia, first by legislation in 1950 and later by referendum, in 1951.See Menzies in Frank Crowley (1973) Modern Australia in Documents, 1939–1970. p.222-226. Wren Publishing, Melbourne. While both attempts were unsuccessful, further international events such as the defection of minor Soviet Embassy official Vladimir Petrov, added to a sense of impending threat that politically favoured Menzies’ Liberal-CP government, as the Labor Party pushed centralist economics and split over concerns about the influence of the Communist Party over the Trade Union movement, resulting in a bitter split in 1955 and the emergence of the breakaway Democratic Labor Party (DLP). The DLP remained an influential political force, often holding the balance of power in the Senate, until 1974; its preferences supported the Liberal and Country Party.Jan Bassett (1986) p.75-6 The Labor party was led by H. V. Evatt after Chifley's death in 1951. Evatt retired in 1960, and Arthur Calwell succeeded him as leader, with a young Gough Whitlam as his deputy.

Menzies presided over a period of sustained economic boom and the beginnings of sweeping social change – with the arrivals of rock and roll music and television in the 1950s. In 1956, television in Australia began broadcasting, Melbourne hosted the Olympics and, for the first time, performing artist Barry Humphries performed the character of Edna Everage as a parody of a house-proud housewife of staid 1950s Melbourne suburbia (the character only later morphed into a critique of self-obsessed celebrity culture). It was the first of many of his satirical stage and screen creations based around quirky Australian characters.

In 1958, Australian country music singer Slim Dusty, who would become the musical embodiment of rural Australia, had Australia's first international music chart hit with his bush ballad "A Pub with No Beer", while rock and roller Johnny O'Keefe's Wild One became the first local recording to reach the national charts, peaking at #20. Before sleeping through the 1960s Australian cinema produced little of its own content in the 1950s, but British and Hollywood studios produced a string of successful epics from Australian literature, featuring home grown stars Chips Rafferty and Peter Finch.

Menzies remained a staunch supporter of links to the monarchy and British Commonwealth and formalised an alliance with the United States, but also launched post-war trade with Japan, beginning a growth of Australian exports of coal, iron ore and mineral resources that would steadily climb until Japan became Australia's largest trading partner.

In the early 1950s, the Menzies government saw Australia as part of a "triple alliance", in concert with both the US and traditional ally Britain.Glen Barclay and Joseph Siracusa (1976) Australian American Relations Since 1945. p.35-49. Holt, Rinehart and Winston, Sydney. At first, "the Australian leadership opted for a consistently pro-British line in diplomacy", while at the same time looking for opportunities to involve the US in South East Asia.Glen Barclay and Joseph Siracusa (1976) p.35 Thus, other than the Korean War, the government also committed military forces to the Malayan Emergency and hosted British nuclear tests after 1952.See Adrian Tame and F.P.J Robotham (1982) Maralinga; British A-Bomb, Australian legacy. p.179 Fontana Books, Melbourne. Australia was also the only Commonwealth country to offer support to the British during the Suez Crisis.E.M. Andrews (1979) A History of Australian Foreign Policy. P.144 Longman Cheshire, Melbourne.

Menzies oversaw an effusive welcome to Queen Elizabeth II on the first visit to Australia by a reigning monarch, in 1954. However, as British influence declined in South East Asia, the US alliance came to have greater significance for Australian leaders and the Australian economy. British investment in Australia remained significant until the late 1970s, but trade with Britain declined through the 1950s and 1960s. In the late 1950s the Australian Army began to re-equip using US military equipment. In 1962, the US established a naval communications station at North West Cape, the first of several built over the next decade.Glen Barclay and Joseph Siracusa (1976) p.63Also see Desmond Ball (1980) A suitable piece of real estate; American Installations in Australia. Hale and Iremonger. Sydney. Most significantly, in 1962, Australian Army advisors were sent to help train South Vietnamese forces, in a developing conflict the British had no part in.

The ANZUS security treaty, which had been signed in 1951, had its origins in Australia's and New Zealand's fears of a rearmed Japan, but found new impetus through anti-communism. Its obligations on the US, Australia and New Zealand are vague, but its influence on Australian foreign policy thinking, at times significant.See discussion on the role of ANZUS in Australia's commitment to the Vietnam War in Paul Ham (2007) Vietnam; The Australian War. p.86-7 Harper Collins Publishers, Sydney. The SEATO treaty, signed only three years later, clearly demonstrated Australia's position as a US ally in the emerging cold war. On 26 November 1967, Australia became the seventh nation to put a satellite into Earth orbit, launching WRESAT from Woomera.

When Menzies retired in January 1966, he was replaced as Liberal leader and prime minister by Harold Holt. The Holt government increased Australian commitment to the growing War in Vietnam; oversaw conversion to decimal currency and faced Britain's withdrawal from Asia by visiting and hosting many Asian leaders and by expanding ties to the United States, hosting the first visit to Australia by an American president, his friend Lyndon B. Johnson. Significantly, Holt's government introduced the Migration Act 1966, which effectively dismantled the vestigial mechanisms of the White Australia policy and increased access to non-European migrants, including refugees fleeing the Vietnam War. Holt also called the 1967 Referendum which removed the discriminatory clause in the Constitution of Australia which excluded Aboriginal Australians from being counted in the census – the referendum was one of the few to be overwhelmingly endorsed by the Australian electorate (over 90% voted 'yes').