Mexico is a federal democratic republic divided into 31 states and the Federal District, which is the seat of government. The Constitution, enacted in 1917 after a long and bloody Revolution, is the basic, supreme set of laws on which the country's overall organization is based. It organically governs the people of Mexico, the holder of national sovereignty.

The Constitution states that the power to rule Mexico is divided between three branches. These are the Presidency, the Congress and the Courts.

The executive branch of power is held by the President of the Republic, who is elected through universal, secret vote for a term of six years with no possibility of reelection.

The legislative branch of power is exercised by the congress, known as the Congress of the Union, which consists of a Chamber of Deputies and the Chamber of Senators. Both Chambers are responsible for drafting, adopting and issuing laws, and for supervising public accounts.

The Chamber of Deputies is made up of 500 representatives elected through universal suffrage for a term of three years: 300 are elected through relative majority, while the other 200 are elected on the basis of proportional representation, thereby ensuring the participation of all registered political parties in the Chamber. The Senate is made up of two representatives from each state and another two representing the Federal District. The administrative structure of the Judiciary branch of government is centered on the circuit system. There are 21 circuits with a total of 128 district courts.

The government is divided into three main branches: the federal branch, which exercises power over the states, the state branch when state matters are involved, and the municipal branch, which oversees the political and administrative units that make up the states. The Constitution establishes the municipality as the basis of the territorial division and of the political and administrative organization of the states of the Republic.

A multiparty system forms the basis of democratic coexistence in Mexico. The main political parties are the Institutional Revolutionary Party (PRI), the National Action Party (PAN) and the Party of the Democratic Revolution (PRD). All registered political parties may nominate candidates for local and federal elections.

Mexico has recently changed from a predominant party system to a multiparty system. The different parties compete for public power under legal conditions. Some of the political parties in Mexico are:
 

- CDPPN - PAN - PARM - PAS - PCD - PDS - PRD - PRI - PSN - PT - PVEM Democratic Convergence National Political Party National Action Party Authentic Revolutionary Mexican Party Social Alliance Party Democratic Centre Party Social Democracy Party Party of the Democratic Revolution Institutional Revolutionary Party Nationalist Society Party Labour Party Green Ecological Mexican Party