National Congress of Chile
The National Congress of Chile is the national legislature of Chile.
Notably, this legislature convenes in Valparaíso rather than Santiago.
Chamber of Deputies
The Chamber of Deputies (Cámara de Diputadas y Diputados) is composed of 155 members; it is led by a president that by current convention rotates among the parties in the governing coalition.
Deputies are elected by party list proportional representation within 28 electoral districts, each holding between 3 and 8 seats.
Up to the 2013 general elections, there were instead 120 members elected from 2-member districts. This was reformed for the 2017 general elections.
Senate
The Senate is composed of 50 members.
Senators are elected directly in 16 constituencies, each holding between 2 and 5 seats. Senators serve staggered 8-year terms, such that 25 seats are voted on in any general election.
Up to 2005, there were instead 40 members, of which up to 20 were elected at a time. Per to the constitutional amendments passed in the June 1989 referendum, individuals could be appointed as senators for life. This designation had been granted only twice: president Eduardo Frei Ruiz-Tagle after he left office, and Pinochet when he resigned as commander-in-chief in 1998. As a result, every other senatorial election had two unelected seats taken out of the total to be voted on.
In 2005 the constitution was amended to revoke these appointments. Note that Pinochet had already resigned his seat a couple years prior; furthermore Frei won an elected seat shortly losing his lifelong term. This nonetheless brought the number of seats down to 38.
In the 2017 general elections, 5 additional seats were elected (so 23 of 43, up from 18 of 38.). In the 2021 general elections, 7 additional seats were elected (so 27 of 50). In the 2025 general elections, the terms will be normalized such that 25 of 50 seats are voted on in any general election.