The Parliament of South Australia is the bicameral legislature of the Australian state of South Australia. It consists of the 47-seat House of Assembly (lower house) and the 22-seat Legislative Council (upper house). General elections are held every 4 years, with all of the lower house and half of the upper house filled at each election. It follows a Westminster system of parliamentary government with the executive branch required to both sit in parliament and hold the confidence of the House of Assembly. The parliament is based at Parliament House on North Terrace in the state capital of Adelaide.

Unlike the federal parliament and the parliaments of most other states, the South Australian Constitution does not define the parliament as including either the monarch or the governor of South Australia as one of its constituent parts. However, the constitution also vests legislative power in the state's governor acting with the advice and consent of both houses of parliament, making the role of the governor effectively the same as those of the other states.

The parliament may make laws for any matter within South Australia, subject to the Constitution of South Australia. Its power is further limited by the ability for the federal parliament to override it in some circumstances, subject to the Constitution of Australia. Similarly, the Supreme Court of South Australia, and ultimately the High Court of Australia, provides judicial oversight of parliament. The parliament is also vested with other powers, such as the means to investigate matters, conduct research and summon witnesses.

At the founding of the Province of South Australia under the South Australia Act 1834, governance of the new colony was divided between the Governor of South Australia and a Resident Commissioner, who reported to a new body known as the South Australian Colonization Commission. Under this arrangement, there was also a governing Council comprising the Governor, the Judge or Chief Justice, the Colonial Secretary, the Advocate-General and the Resident Commissioner, with broad legislative and executive powers including the imposition of rates, duties, and taxes. This council was sometimes referred to as the "Legislative Council". Confusion and dispute about the division of power between the two roles led to the South Australia Government Act 1838, which combined the role of Resident Commissioner with that of the Governor.

In 1842, the South Australia Act 1842 was passed in order to replace the South Australian Colonisation Commission appointed in 1834 with a more standard British model of government, with a Governor advised by a Legislative Council. The 1842 Act gave the British Government, which was responsible for appointing a Governor and at least seven other officers to the Legislative Council, full control of South Australia as a Crown Colony, after financial mismanagement by the first administration had nearly bankrupted the colony. This new Legislative Council was the first true parliamentary body in South Australia. The Act also made provision for a commission to initiate the establishment of democratic government, electoral districts, requirements for voting rights, and terms of office. Although the old governing Council advising the Governor met at Government House, this new Legislative Council met at a new purpose built chamber on North Terrace. This chamber eventually grew into what is now known as "Old Parliament House".

The Australian Colonies Government Act 1850 was a landmark development which granted representative constitutions to New South Wales, Victoria, South Australia and Tasmania and the colonies enthusiastically set about writing constitutions which produced democratically progressive parliaments with the British monarch as the symbolic head of state. In 1851 elections for the Legislative Council were held. The new Council consisted of 24 members, four official (filling what would be today ministerial positions) and four non-official members, both nominated by the governor on behalf of the Crown, and 16 elected members chosen from single-member districts. The right to vote for these positions was not universal, however, being limited to propertied men. In addition, the reforms meant that the Governor no longer oversaw proceedings, with the role being filled by a Speaker who had been elected by the members.

In 1853 the Legislative Council sent London a Parliament Act 1853 that provided for a new constitution that established a bicameral parliament with an elected lower house and an upper house made up of members nominated for life. The colonists were mistakenly under the impression that only such a scheme would be acceptable to the British Government. The Governor, Sir Henry Young, had been advised that this was not the case but he kept this information to himself. The colonists were furious and 5,000 petitioned Westminster to give them two elected houses. The offending constitution was returned and in 1855, a new Legislative Council was elected with a mandate to establish something far more radical and democratic than had been seen in the British Empire before.

This was expressed by the Constitution Act 1856 (headed "1855–6: No. 2" and followed by the long title "An Act to establish a Constitution for South Australia, and to grant a Civil List to Her Majesty") establishing the constitution of the Parliament of the Province of South Australia.