Twelve lessons across the five units and six countries: regimes, legitimacy, institutions, culture, electoral and party systems, development and data skills, with interactive explorers.
A reasoning guide to AP Comparative Government and Politics, not a full course. Unit titles, weightings, the six countries and the exam format follow the College Board pages. Country details are stable structural facts for study and can change; confirm current facts in your textbook and news. Example numbers are invented.
None.
Course outline
States, nations, regimes and governments
Separate four terms the exam uses precisely, and classify political systems.
Legitimacy and sources of authority
Explain why people accept rule and how that supports stability.
Executive and legislative structures
Compare parliamentary, presidential and semi-presidential systems.
Judiciaries and constitutions
Describe judicial independence, review and how constitutions limit power.
Federal and unitary states, devolution
Explain how power is divided between levels of government.
Political culture, cleavages and civil society
Identify cleavages and explain how they shape politics.
Participation, rights and the limits of dissent
Compare how citizens take part in politics under different regimes.
Electoral systems: from votes to seats
Compare plurality, proportional and mixed systems and measure disproportionality.
Party systems and how many parties matter
Describe party systems and count the effective number of parties.
Democratization, economic change and development
Describe liberalization, privatization and growth with simple calculations.
Reading data: tables, percent change and percentage points
Handle the quantitative stimuli that appear in multiple-choice and free-response questions.
Six countries side by side
Build a comparison table for the six countries in the course.
Sources and curriculum note
Reviewed October 7, 2026. Confirm format on the College Board site for your exam year.
Read every lesson below. The interactive reader above contains the same explanations, with visual tools and quizzes.
1. States, nations, regimes and governments
Learning goal: Separate four terms the exam uses precisely, and classify political systems.
A state is an organization with sovereignty: the ultimate authority over a territory and a population, with a monopoly on the legitimate use of force. A nation is a group of people who share an identity, such as language, history or culture. A nation-state aims to match the two, but many states hold several nations, and some nations have no state.
A regime is the set of rules and institutions that decide how power is gained and used, such as a democracy or an authoritarian system. A government is the particular group of people in charge at a time. Governments change often within a regime. A change of regime is far larger, for example from a one-party state to a multiparty democracy.
Political systems are often described on a spectrum from democratic to authoritarian. In democracies, leaders are chosen through free and fair competitive elections and civil liberties are protected. In authoritarian systems, power is concentrated and competition and dissent are limited. Many real systems fall in between, so scholars talk about degrees and hybrid regimes.
On the exam, define the concept first, then apply it to a country. For example, say that the United Kingdom's government changes after an election while its regime stays parliamentary and democratic. Keep the vocabulary exact.
Worked example
A party loses an election and a new party forms the government. Which level changed?
The government changed.
The regime rules did not.
The state did not.
Government only.
Practice problem and solution
In an exam, you list state, nation, regime and government. How many distinct terms is that? Enter a number.
State, nation, regime, government.
Mental model: State = sovereignty. Nation = identity. Regime = rules. Government = people in office.
Common trap: Using government and regime as synonyms.
2. Legitimacy and sources of authority
Learning goal: Explain why people accept rule and how that supports stability.
Legitimacy is the widespread belief that a government has the right to rule. A legitimate government needs less force to gain obedience. Max Weber described three ideal types of authority: traditional (custom or heredity), charismatic (the personal qualities of a leader) and legal-rational (rules and offices that apply to everyone).
Legitimacy can also come from performance, such as growth, security and public services, and from nationalism or ideology. Democratic elections create legitimacy through consent. Regimes that rely on performance can lose support when the economy slows, so many authoritarian systems also use ideology and control of information.
Stability is the capacity of a political system to continue without major disruption. It depends on legitimacy, institutions that handle conflict, and the balance between the state's capacity and the demands placed on it. Instability can appear as protests, coups, civil conflict or repeated breakdown of governments.
A careful answer names the type of authority, gives evidence for it in a case, and notes limits: a regime may look stable while support is shallow, and legitimacy can vary across groups.
Worked example
A leader rules because of a hereditary title. Which type of authority is that?
Based on heredity.
That is custom.
Weber's traditional type.
Traditional.
Practice problem and solution
How many types of authority did Weber describe? Enter a number.
Traditional, charismatic, legal-rational.
Mental model: Legitimacy is belief in the right to rule. Weber: traditional, charismatic, legal-rational.
Common trap: Assuming stability proves legitimacy.
3. Executive and legislative structures
Learning goal: Compare parliamentary, presidential and semi-presidential systems.
In a parliamentary system, the chief executive (a prime minister) comes from the legislature and stays in office only while keeping its confidence. Executive and legislature are fused. In the United Kingdom, the prime minister leads the party or coalition that can command a majority in the House of Commons.
In a presidential system, voters elect the president separately from the legislature and the president serves a fixed term. The powers are separated, so the president and the legislature can be controlled by different parties. Mexico and Nigeria are federal presidential systems.
A semi-presidential system has both a directly elected president and a prime minister. Russia's constitution gives the president very large powers, including naming the prime minister, and the arrangement is often called super-presidential in practice. The balance of power depends on the party system and on how much the president controls the legislature.
Compare on four questions: who chooses the chief executive, who can remove them, how independent the legislature is, and whether the head of state and the head of government are the same person.
Worked example
A prime minister loses a confidence vote. What does this mean in a parliamentary system?
The government must resign or call an election.
Confidence is required.
Only in parliamentary systems.
Government falls.
Practice problem and solution
How many systems are compared in this lesson? Enter a number.
Parliamentary, presidential and semi-presidential.
Common trap: Assuming every president has the same power.
4. Judiciaries and constitutions
Learning goal: Describe judicial independence, review and how constitutions limit power.
A constitution sets out the structure of government and the limits on it. The United Kingdom has an uncodified constitution drawn from statutes, conventions and court decisions, and Parliament is sovereign. Mexico, Nigeria, Russia, China and Iran have written constitutions.
Judicial review is the power of courts to strike down laws or actions that conflict with the constitution. It is stronger where a constitutional court has real independence. In the UK, courts do not strike down Acts of Parliament, though they can declare incompatibility with human rights law.
Judicial independence depends on how judges are appointed and removed, their salaries and the willingness of other branches to obey rulings. In authoritarian systems courts often serve the ruling party. In Iran the Guardian Council reviews laws for conformity with Islamic law and the constitution and vets candidates.
Think of a court as a check only if it can rule against powerful actors and be obeyed. Evidence includes cases that went against the government, protections for judges, and public trust.
Worked example
A court strikes down a law and the government complies. What does that suggest?
The court has independence.
The ruling was obeyed.
A functioning check.
Judicial review in practice.
Practice problem and solution
How many factors for judicial independence are listed in the table? Enter a number.
Appointment, tenure and pay, compliance.
Mental model: A court checks power only if it can rule against it and be obeyed.
Common trap: Confusing a written right with an enforced right.
5. Federal and unitary states, devolution
Learning goal: Explain how power is divided between levels of government.
In a unitary state, the central government holds ultimate authority and can create or change lower levels. In a federal state, the constitution divides power between national and regional governments, so the national government cannot simply abolish the regions. Mexico and Nigeria are federal, and Russia is nominally a federation.
Devolution is the transfer of some powers from the center to regional bodies that the center could in principle take back. The United Kingdom devolved powers to Scotland, Wales and Northern Ireland, although it remains a unitary state because Parliament is sovereign.
Federalism helps accommodate regional and ethnic differences, as in Nigeria, which has 36 states and a federal capital territory. It can also create conflict over revenue and resources. In practice, central control varies. In Russia, regional leaders operate within a strong central structure, and in China local governments carry out national policy under party supervision.
To analyze a case, ask what powers belong to each level, who controls the money, and whether the center can override the regions.
Worked example
Nigeria has 36 states plus a federal capital territory. How many first-level units is that?
36 states.
Plus the capital territory.
36 + 1.
37.
Practice problem and solution
Nigeria has 36 states and a federal capital territory. How many units in total? Enter a number.
Learning goal: Identify cleavages and explain how they shape politics.
Political culture is the set of shared beliefs, values and attitudes about politics. It shapes what people expect from the government and how they participate. Culture can be a source of unity and also of division when groups hold very different views.
A cleavage is a deep social division that organizes politics. Common examples are ethnicity, religion, region, class and language. In Nigeria, regional, ethnic and religious divisions are central and shape party politics and the Federal Character principle, which tries to spread appointments across groups. In the UK, regional and national identities matter, as in Scotland.
Civil society is the set of voluntary organizations between the individual and the state, such as unions, religious groups and advocacy groups. In democracies it can hold government to account. In authoritarian systems the state may control, co-opt or restrict civil society, as in China's registration rules for organizations.
To analyze, name the cleavage, say whether it is reinforcing or cross-cutting, and describe how institutions manage it. Cross-cutting cleavages tend to reduce conflict because people share some identities with those they differ from on others.
Worked example
A person is in a majority on language but a minority on religion. What kind of cleavage structure is that?
Different divisions do not line up.
That is cross-cutting.
It tends to reduce conflict.
Cross-cutting.
Practice problem and solution
How many cleavage examples are in the first table? Enter a number.
Ethnic, regional, class.
Mental model: Cleavages organize politics; cross-cutting ones reduce conflict.
Common trap: Treating a country's culture as uniform.
7. Participation, rights and the limits of dissent
Learning goal: Compare how citizens take part in politics under different regimes.
Political participation includes voting, joining parties, contacting officials, protesting and organizing. In democracies, civil liberties such as freedom of speech, assembly and the press let citizens take part and criticize government without fear of punishment.
In authoritarian systems, participation may be channelled and limited. Elections can occur but candidates may be screened, as in Iran where the Guardian Council vets candidates, or competition may be tightly restricted. Protest may be permitted in some forms and punished in others, and the government may use censorship and surveillance.
Regimes respond to dissent with a mix of repression, concessions and co-optation. Concessions can calm protest in the short run. Repression can raise costs for opponents but may also increase grievances. Social media can lower organizing costs but also gives states new tools for monitoring.
A balanced answer separates formal rights, such as those in the constitution, from practice, and gives evidence for each. A constitution that promises rights does not guarantee them.
Worked example
A constitution promises free speech, but critics are jailed. What should you conclude?
Rights exist on paper but are not respected in practice.
Formal and actual rights differ.
Check evidence of practice.
Gap between law and practice.
Practice problem and solution
How many responses to dissent are in the table? Enter a number.
Repression, concessions, co-optation.
Mental model: Participation depends on rights in practice. Regimes mix repression, concessions and co-optation.
Common trap: Treating constitutional text as proof of practice.
8. Electoral systems: from votes to seats
Learning goal: Compare plurality, proportional and mixed systems and measure disproportionality.
In a single-member district plurality system, also called first past the post, the candidate with the most votes in a district wins. It is used for the UK House of Commons. It tends to give large parties a bigger share of seats than votes and makes it hard for small national parties to win seats unless their support is concentrated.
In proportional representation (PR), parties win seats in proportion to their votes, using party lists. It tends to produce more parties and coalition governments. Mixed systems combine both: Mexico's Chamber of Deputies has 300 single-member seats and 200 PR seats, and Russia's State Duma has used mixed and fully proportional rules at different times.
A simple measure of disproportionality is the Gallagher index: the square root of half the sum of squared differences between each party's vote share and seat share, in percentage points. A value near 0 means seats match votes closely. A large value means the system distorts the result.
On the exam, link the system to its effects: plurality tends toward two large parties and single-party majorities, PR toward multiple parties. These are tendencies, not laws, and they depend on how voters are spread.
Worked example
Vote shares A 40, B 35, C 25; seat shares A 50, B 35, C 15. Gallagher index?
Differences: 10, 0, -10.
Squares: 100, 0, 100.
Half the sum: 100.
Square root: 10.
Practice problem and solution
Votes 40, 35, 25 and seats 50, 35, 15. What is the Gallagher index? Enter a number.
sqrt(0.5 x (100 + 0 + 100)) = 10.
Mental model: Plurality favors big parties; PR is more proportional. Gallagher index measures the gap.
Common trap: Treating tendencies as laws.
9. Party systems and how many parties matter
Learning goal: Describe party systems and count the effective number of parties.
A party system is the pattern of competition among parties. In a one-party system, only one party is legally allowed to rule, as with the Chinese Communist Party. A dominant-party system has elections with several parties but one party wins repeatedly, as the PRI did in Mexico for most of the twentieth century. Competitive systems may have two main parties or many.
Electoral rules shape party systems. Duverger's law says that plurality rules in single-member districts tend toward two parties, while PR allows more. Party systems also depend on cleavages and history, so the link is a tendency. In Nigeria, parties have to show national spread, a rule designed to limit purely ethnic parties.
The effective number of parties is N = 1 / (sum of squared shares). If four parties each have 25 percent, N = 4. If one party has 70 percent and the others share 30, N is much lower than the raw party count. It counts parties by their size, not just their existence.
Use it to compare systems on the same scale. A raw count of parties can mislead when most are tiny.
Worked example
Four parties have equal shares of 0.25. Effective number?
Squares: 0.0625 each.
Sum: 0.25.
1 / 0.25.
4.
Practice problem and solution
Shares 0.5, 0.3, 0.2. Effective number of parties, to 2 decimals?
Sum of squares = 0.38, so 1/0.38 = 2.63.
Mental model: N = 1 / sum of squared shares. Plurality tends toward two parties.
Common trap: Counting tiny parties as equal to big ones.
10. Democratization, economic change and development
Learning goal: Describe liberalization, privatization and growth with simple calculations.
Democratization is the process of moving toward democracy: free and fair elections, protection of rights and accountable institutions. It can be gradual or sudden and can reverse, a process called democratic backsliding. Transitions need both change at the top and groups that push for it.
Economic policy changes also matter. Import substitution industrialization tries to build domestic industry by protecting it, while liberalization lowers trade barriers and reduces state control. Privatization shifts firms from state to private ownership. Countries such as Mexico moved toward open trade in the late twentieth century, and China allowed market reforms while the Communist Party kept control of politics.
Countries use measures such as GDP per capita, growth and inequality to compare development. A useful rule is the rule of 70: the doubling time of a quantity growing at g percent a year is about 70 / g years. At 7 percent growth an economy doubles in about 10 years. The rule is an approximation.
A careful answer links economic change to politics. Growth can raise legitimacy and demands for participation, while a crisis can undermine a regime. Evidence matters: cite specific measures, not general statements.
Worked example
An economy grows at 5 percent a year. Approximate doubling time?
Rule of 70.
70 / 5.
= 14.
14 years.
Practice problem and solution
Growth is 3.5 percent a year. Doubling time in years by the rule of 70?
70 / 3.5 = 20.
Mental model: Rule of 70: doubling time = 70 / growth rate. Link economics to legitimacy.
Common trap: Treating economic growth as causing democracy automatically.
11. Reading data: tables, percent change and percentage points
Learning goal: Handle the quantitative stimuli that appear in multiple-choice and free-response questions.
The exam includes questions that give a table, graph, map or infographic and ask what it shows. Read the title, axes, units and source first. Then answer only what the data support. A claim about a cause usually needs more than the data shown.
Percent change is (new - old) / old x 100. Percentage points describe the difference between two percentages. If voter turnout goes from 50 to 60 percent, that is a rise of 10 percentage points and a rise of 20 percent. Mixing the two is one of the most common mistakes.
When you compare countries, check that the measure is the same and the years match. A raw number, such as total population, can mislead, so rates and shares are often better. Look at the scale on the axis, because a truncated axis can exaggerate small differences.
State a pattern, give the evidence, and then add a limit. For example: turnout rose from 50 to 60 percent over the period, which is 10 percentage points, but the data do not say why.
Worked example
Turnout goes from 50 to 60 percent. Percent change?
(60 - 50) / 50.
= 0.2.
20 percent.
Also 10 percentage points.
Practice problem and solution
Turnout rises from 50 to 60 percent. What is the percent change? Enter a number.
(60 - 50) / 50 x 100 = 20.
Mental model: Percent change is relative; percentage points are absolute. Read units and limits.
Common trap: Confusing percent change with percentage points.
12. Six countries side by side
Learning goal: Build a comparison table for the six countries in the course.
The course studies six countries: China, Iran, Mexico, Nigeria, Russia and the United Kingdom. A table of basic features, built from the course framework, helps with comparison questions. Details change, so use it as a study aid and check current facts for any real case.
United Kingdom: parliamentary democracy, unitary with devolution, plurality elections for the Commons, uncodified constitution. Mexico: federal presidential system with a mixed electoral system for the lower chamber. Nigeria: federal presidential system with a bicameral legislature and a strong role for ethnic and regional balance. Russia: federation with a dominant presidency and a mixed record on competition.
China: one-party state led by the Chinese Communist Party, with the National People's Congress as the formal highest organ of state power. Iran: a republic with an unelected Supreme Leader and a Guardian Council that vets candidates, alongside an elected president and parliament. These two combine elected bodies with limits on competition.
Compare in pairs on a concept, not by country order. For legitimacy, compare the UK and Iran. For federalism, compare Mexico and Nigeria. For authoritarian control, compare China and Russia.
Worked example
How many countries does the course study?
China, Iran, Mexico, Nigeria, Russia, UK.
Count them.
Six.
6.
Practice problem and solution
How many countries are in the course? Enter a number.
China, Iran, Mexico, Nigeria, Russia, United Kingdom.
Mental model: Six countries: China, Iran, Mexico, Nigeria, Russia, UK. Compare by concept.
Common trap: Memorizing facts without a comparison concept.