The House of Lords Act 1999 is an Act of the Parliament of the United Kingdom that reformed the House of Lords, one of the chambers of Parliament. The Act was given Royal Assent on 11 November 1999. For centuries, the House of Lords had included several hundred members who inherited their seats ; the Act removed such a right. However, as part of a compromise, the Act did permit ninety-two hereditary peers to remain in the House. Another ten were created life peers to enable them to remain in the House.

The Parliament of the United Kingdom of Great Britain and Northern Ireland is the supreme legislative body of the United Kingdom, and may also legislate for the Crown Dependencies and the British Overseas Territories. It meets at the Palace of Westminster in London. Parliament possesses legislative supremacy and thereby holds ultimate power over all other political bodies in the United Kingdom and the Overseas Territories. While Parliament is bicameral, it has three parts: the sovereign, the House of Lords, and the House of Commons. The three parts acting together to legislate may be described as the King-in-Parliament. The Crown normally acts on the advice of the prime minister, and the powers of the House of Lords are limited to only delaying legislation; thus power is de facto vested in the House of Commons.