The ruling party or governing party in a democratic parliamentary system is the incumbent political party or coalition of the majority in parliament, that administers the affairs of state. Within a parliamentary system, the majority in the legislature also controls the executive branch of government, thus leaving no possibility of dueling parties concurrently occupying the executive and legislative branches of government, such as in an American style presidential system where the party of the president does not necessarily also have a legislative majority.
A ruling party is also used to describe the party of one-party states, such as the Communist Party of China in the People's Republic of China. In his political manifesto The Green Book, the late Libyan leader Muammar al-Gaddafi attacked the ability of the ruling party, using it as a basis for his opposition to partisan politics. This is an example of methods and rationale that dictatorships espouse to establish an unchanging monolithic society, tyrannical rule and , without any participatory opportunities offered to a population.