In a parliamentary system, the head of state is usually separate from the head of government. The head of state in a parliamentary system is either a monarch, as in Britain, or a president, as in India, the latter normally elected by the legislature or an electoral college of national and regional legislatures. The head of government is the prime minister. The prime minister and the cabinet have to be appointed from among the members of Parliament.

In most parliamentary systems, the president appoints the prime minister, but must choose as the prime minister that member of Parliament who has the support of the majority of parliamentarians, which usually means the leader of the majority party or the leader of a coalition of parties, which together have the support of the majority. Sometimes, the prime minister is appointed by or on the advice of the speaker of the legislature (as in Sweden), following the same principle of majority support; and occasionally, the prime minister is directly elected by the legislature (as in Papua New Guinea or the Solomon Islands). The prime minister appoints the members of the cabinet.

The head of state may also, in some circumstances, have the power to remove a government, but otherwise, his or her role is mainly ceremonial. The real power of government is vested in the cabinet, acting under the prime minister. The cabinet operates on the principle of collective responsibility, which means that decisions on policy must be made by the entire cabinet and defended by all ministers. The government is at all times responsible to Parliament and must explain and defend its policy to its members. Parliament can at any time remove the government by passing a vote of no confidence. In many parliamentary systems, the prime minister can also ask for and secure the dissolution of Parliament, subject to certain restrictions; the conflict between the prime minister and Parliament is then resolved in the resulting general election.