The National Assembly of Lebanon is the Lebanese national legislature. It is elected to a four-year term by universal adult suffrage in multi-member constituencies, apportioned among Lebanon's diverse Christian and Muslim denominations. Its major functions are to elect the President of the republic, to approve the government (although appointed by the President, the Prime Minister, along with the Cabinet, must retain the confidence of a majority in the National Assembly), and to approve laws and expenditure.

A unique feature of the Lebanese system is the principle of "confessional distribution": each religious community has a allotted number of deputies in the National Assembly. In elections held between 1932 and 1972 (the last till after the Lebanese Civil War), seats were apportioned between Christians and Muslims in a 6:5 ratio, with various denominations of the two faiths allocated representation roughly proportional to their size. By the 1960s, Muslims had become openly dissatisfied with this system, aware that their own higher birthrate and the higher emigration rate among Christians had by this time almost certainly produced a Muslim majority, which the parliamentary distribution did not reflect. Christian politicians were unwilling to abolish or alter the system, however, and it was one of the factors in the 1975-1990 civil war. The Taif Agreement of 1989, which ended the civil war, reapportioned the National Assembly to provide for equal representation of Christians and Muslims, with each electing 64 of the 128 deputies.

Although distributed confessionally, all members, regardless of their religious faith, are elected by universal suffrage, forcing politicians to seek support from outside of their own religious communities, unless their co-religionists overwhelmingly dominate their particular constituency.

The changes stipulated by the Taif Agreement are set out in the table below:

                       BEFORE TAIF              AFTER TAIF  
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Religion
    Denomination       Allocated seats          Allocated seats                               
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Christian              54                       64
    Maronite               30                       34
    Greek Orthodox         11                       14
    Greek Catholic          6                        8
    Armenian Orthodox       4                        5
    Armenian Catholic       1                        1
    Protestant              1                        1
    Other Christians        1                        1
Muslim                 45                       64
    Sunni                  20                       27
    Shi'a                  19                       27
    Druze                   6                        8
    Alawite                 0                        2
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Total                      99                      128
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Numerous political parties exist in Lebanon, but their role in politics is much less significant than in most parliamentary democracies. Many "parties" are little more than ad-hoc electoral lists, formed by negotiation among influential local figures representing the various confessional communities; these lists usually function only for the purpose of the election, and do not form identifiable groupings in the National Assembly subsequently. Other parties are personality-based, often comprising followers of a present or past political leader or warlord. Few parties are based, in practice, on any particular ideology, although in theory most claim to be. No single party has ever won more than 12.5 percent of the total number of seats in the National Assembly, and no coalition has ever won more than a third of the total.

The system of multi-member constituencies has been criticized over the years by many politicians, who claim that it is easy for the government to gerrymander the boundaries. The Baabda-Aley constituency, established for the 2000 election, is a case in point: the strongly Christian area of Aley (in the east of Beirut) were combined, in a single constituency, with the Muslim areas of Baabda. The combined constituency had a Muslim majority, meaning that although several seats within the constituency were allocated to Christians, they had to appeal to an electorate dominated by Muslims. Many opposition politicians, mostly Christians, have claimed that the constituency boundaries were extensively gerrymandered in the elections of 1992, 1996, and 2000 to produce a pro-Syrian majority. Unless and until the myriad religious and political factions can agree on an alternative electoral system, the controversy is unlikely to be resolved.

The Speaker of the National Assembly, who must be a Shi'a Muslim, is elected to a four-year term. He forms part of a "troika" together with the President (required to be a Maronite Christian) and the Prime Minister (a Sunni Muslim). The current speaker is the leader of the Amal Party, Nabih Berri.