Spain is a constitutional monarchy in which the King is the titular head of the state, while the actual governmental and administrative powers are exercised by the Prime Minister, the deputy Prime Minister, and the other ministers who together comprise the Council of Ministers. The offices of the Prime Minister and the Council of Ministers in Spain were established under the Constitution of 1978.

While the King inherits the Spanish crown, the Prime Minister and the Council of Ministers in Spain have to establish their claim to power by winning the national elections, which take place every four years. The Prime Minister is not directly elected by the people, but indirectly elected by the members of the Parliament, or the Cortes Generales, as it is known in Spain. The Speaker of a newly elected Cortes invites the leader of the winning party to become a candidate for the position of the Prime Minister. He communicates the name of the candidate to the Spanish monarch, who formally submits his name before the Cortes.

A two-day long debate follows between the candidate and the legislature, in which the candidate states what his government hopes to achieve. If the candidate wins the confidence of the legislature by receiving a majority of votes (currently 176 out of 350 MPs), then the process is complete. If not, a second vote is scheduled two days later in which a simple plurality (i.e. more "yes" than "no" votes) is required. If this procedure also fails, the King proposes other candidates until one gains a vote of confidence. If no candidate succeeds within two months of the first vote, the king dissolves the Cortes and calls for new elections.

When a candidate wins the vote of confidence, he is officially appointed as the Prime Minister by the King. He can then appoint the Council of Ministers. As has already been mentioned, together, the Prime Minister and the Council of Ministers in Spain constitute the highest executive body in the state. The Prime Minister's first duty is to form the Cabinet. His second duty is to oversee the activities of the individual ministers. His third duty is to provide leadership and direction to the government.

The Council of Ministers is responsible for formulating and implementing policy. It exercises all kinds of and administrative functions, and supervises the functioning of the military. It is responsible for national security and defense. Individual ministers often have to resolve administrative conflicts within their departments. Although vested with a great deal of discretion and autonomy, the ministers are ultimately responsible to the Prime Minister and accountable to the Cortes. The Prime Minister and the Council of Ministers in Spain are forbidden to hold any additional posts outside the government, and are prohibited from engaging in any professional or commercial activity.