Responsible government is a conception of a system of government that embodies the principle of parliamentary accountability, the foundation of the Westminster system of parliamentary democracy. Governments in Westminster democracies are responsible to parliament rather than to the monarch, or, in a colonial context, to the imperial government, and in a republican context, to the president, either in full or in part. If the parliament is bicameral, then the government is responsible first to the parliament's lower house, which is more representative than the upper house, as it usually has more members and they are always directly elected.

The Westminster system, or Westminster model, is a type of parliamentary government that incorporates a series of procedures for operating a legislature, first developed in England. Key aspects of the system include an executive branch made up of members of the legislature, and that is responsible to the legislature; the presence of parliamentary opposition parties; and a ceremonial head of state who is separate from the head of government. The term derives from the Palace of Westminster, which has been the seat of the Westminster Parliament in England and later the United Kingdom since the 13th century. The Westminster system is often contrasted with the presidential system that originated in the United States, or with the semi-presidential system, based on the government of France.