A bicameral legislature is a lawmaking body split into two separate chambers (an upper and lower house). In AP Comparative Government, the UK, Russia, Mexico, and Nigeria have bicameral legislatures, while China's National People's Congress and Iran's Majles are unicameral.
A bicameral legislature is a lawmaking body divided into two chambers, usually called an upper house and a lower house. Splitting the legislature in two slows down lawmaking on purpose. It forces a second look at bills and often gives different groups (regions, states, or elites) their own seat at the table.
For AP Comp Gov, the split among the six course countries is the thing to memorize. Four are bicameral: the UK (House of Commons + House of Lords), Russia (State Duma + Federation Council), Mexico (Chamber of Deputies + Senate), and Nigeria (House of Representatives + Senate). Two are unicameral: China's National People's Congress and Iran's Majles. The pattern isn't random. Federal states like Russia, Mexico, and Nigeria use the upper house to represent regions or states. Bicameralism also comes in flavors. The UK is asymmetric because the elected Commons holds nearly all real power while the unelected Lords can mostly just delay bills. Nigeria is closer to symmetric, with two chambers that both genuinely matter.
This term lives in Unit 2: Political Institutions, specifically Topic 2.6: Legislative Systems, and supports learning objective 2.6.A, which asks you to describe legislative structures and functions in the course countries. The essential knowledge (PAU-3.E.1) explicitly identifies China and Iran as unicameral, which means the exam expects you to know the other four are bicameral and to explain what each chamber does. Bicameralism is also a perfect comparison hook. It connects to regime type (authoritarian legislatures like Russia's mostly rubber-stamp), to federalism (upper houses representing regions), and to legitimacy (elected vs. appointed chambers). If a question asks you to compare legislatures across countries, this is usually where the answer starts.
Keep studying AP Comparative Government Unit 2
Unicameral Legislatures: China's NPC and Iran's Majles (Unit 2)
The flip side of this term. China's National People's Congress is a single chamber the constitution calls the most powerful institution, though in practice the party controls it. Iran's elected Majles is also one chamber, but it legislates under the supervision of the Guardian Council. Knowing which countries are NOT bicameral is half the battle.
Federation Council and Federalism (Unit 2)
Russia's upper house exists to represent its federal subjects, and its members are appointed rather than directly elected. That appointed upper chamber is one clear way Russia's system differs from a pure parliamentary model, where the elected lower house dominates everything.
House of Commons vs. House of Lords: Asymmetric Bicameralism (Unit 2)
The UK shows that two chambers don't have to be equals. The Commons is elected and makes the real decisions; the Lords is unelected and can only delay legislation. When a question says 'asymmetric bicameralism,' it's almost always pointing at the UK.
Proportional Representation and Chamber Composition (Unit 4)
How each chamber gets filled matters as much as how many chambers exist. Mexico, for example, mixes single-member districts and proportional representation to fill its Chamber of Deputies. Election rules from Unit 4 explain why two chambers in the same country can look politically different.
Bicameralism shows up most often in multiple-choice questions that ask you to match structure to country or to compare two countries' legislatures. Typical stems ask which course country's legislature most resembles Nigeria's (Mexico is the closest match, with two elected chambers in a federal presidential system), what makes the UK's bicameralism asymmetric (the unelected, weak House of Lords), or how Russia's appointed Federation Council distinguishes it from a pure parliamentary system. Another favorite move is testing whether you know China's NPC is unicameral, not bicameral. On the FRQ side, this term is built for the Comparative Analysis question. Be ready to describe a legislative structure in one country, then explain how a second country's structure differs and why (federalism, regime type, or historical design). Don't just say 'two houses.' Name the chambers and say what each one actually does.
Iran is unicameral, even though the Guardian Council reviews every law the Majles passes. The Guardian Council is an unelected oversight body of 12 members that vets legislation for compatibility with Islamic law and screens candidates; it doesn't draft or pass legislation as a co-equal house. A real upper chamber, like Nigeria's Senate, is part of the legislature itself. So on the exam, classify Iran's Majles as a unicameral legislature operating under Guardian Council supervision, not as half of a bicameral system.
A bicameral legislature has two chambers, and four AP Comp Gov course countries have one: the UK, Russia, Mexico, and Nigeria.
China's National People's Congress and Iran's Majles are unicameral, and per PAU-3.E.1 you need to be able to describe both.
The UK is the classic case of asymmetric bicameralism because the elected House of Commons holds real power while the unelected House of Lords can only delay bills.
Federal systems like Russia, Mexico, and Nigeria use the upper house to represent regions or states, which links bicameralism directly to federalism.
Iran's Guardian Council supervises the Majles but is not a second legislative chamber, so Iran still counts as unicameral.
On comparison questions, Nigeria's bicameral legislature most closely resembles Mexico's, since both pair two elected chambers with a federal presidential system.
It's a legislature divided into two chambers, an upper and lower house. Among the six course countries, the UK, Russia, Mexico, and Nigeria are bicameral, while China and Iran are unicameral.
No. Iran's Majles is a single elected chamber, so Iran is unicameral. The Guardian Council supervises and vetoes legislation, but it's an unelected oversight body, not a second house of the legislature.
Four of the six: the UK (Commons and Lords), Russia (State Duma and Federation Council), Mexico (Chamber of Deputies and Senate), and Nigeria (House of Representatives and Senate). China and Iran are the unicameral exceptions.
In asymmetric bicameralism, one chamber clearly dominates. The UK is the go-to example, since the unelected House of Lords can mostly just delay what the Commons passes. In more symmetric systems like Nigeria's, both chambers hold real legislative power.
The NPC is a single chamber, so China is unicameral. The constitution names it the government's most powerful institution that elects the president and approves the premier, but in practice it operates under Communist Party control and largely legitimizes executive policy.