The Parliament of British Columbia is composed of three parts: the Lieutenant Governor, the Legislative Assembly, and the Executive Council.

Lieutenant Governor: The Lieutenant Governor is the representative of the Queen of Canada in British Columbia and is responsible for the formal appointment of the Premier and other members of the Executive Council, as well as for the granting of Royal Assent to legislation.

Legislative Assembly: The Legislative Assembly is the law-making body of the province, consisting of 87 elected Members of the Legislative Assembly (MLAs) who represent the 87 electoral districts in British Columbia. The Speaker presides over the proceedings of the Legislative Assembly and ensures that the rules and procedures of the house are followed.

Executive Council: The Executive Council, also known as the Cabinet, is responsible for the administration of the province and is composed of the Premier, who is the head of government, and other members appointed by the Lieutenant Governor on the advice of the Premier. The Cabinet is responsible for making decisions on government policy and for implementing legislation passed by the Legislative Assembly.

In British Columbia, the parliamentary system operates on the principle of responsible government, which means that the government is accountable to the Legislative Assembly and can be removed from office if it loses the confidence of a majority of the members of the house.

The structure of the British Columbia Parliament is based on the Westminster model of parliamentary democracy, which is named after the Palace of Westminster in London, England. The Westminster model originated in the United Kingdom in the 19th century and has been adopted by many former British colonies, including Canada, as well as other countries around the world.

In the Westminster system, the head of state is a constitutional monarch, such as the Queen of Canada, and executive power is exercised by the Cabinet, which is responsible to the elected legislative assembly. This model of government combines elements of parliamentary democracy, such as the election of members of the legislative assembly and the principle of responsible government, with elements of constitutional monarchy, such as the role of the head of state as a symbolic figurehead and the granting of Royal Assent to legislation.

The structure of the British Columbia Parliament reflects the influence of the Westminster model, but has been adapted to reflect the unique political and constitutional context of the province within the Canadian federation.