To write a synthesis essay, read your sources, group them by the ideas they share or dispute, form a thesis about the issue, and build body paragraphs that combine several sources to support each point. The essay is your argument, with sources as evidence.
Synthesis essays appear on the AP English Language exam and across university courses. This guide explains what synthesis means, how to plan with a source grid, how to structure paragraphs, a sample outline and paragraph, and timing advice for the exam.
The Core Steps of a Synthesis Essay
- Read the prompt and identify the issue and task: argue, explain or evaluate.
- Read every source and note its position and key evidence.
- Group sources by the points they support, challenge or complicate.
- Write a thesis that takes a clear, defensible position.
- Build each body paragraph around one point, combining two or more sources.
- Explain how the evidence supports your point in your own commentary.
What Synthesis Means
Synthesis is combining ideas from several sources to create something new: your own argument. It is the opposite of summarising each source in turn.
A synthesis essay asks you to show that you can see how sources relate. Where do they agree? Where do they conflict? What does one add that another misses? Your answers to those questions become the backbone of the essay.
| Summary approach | Synthesis approach |
|---|---|
| One paragraph per source | One paragraph per idea, using several sources |
| Reports what each author says | Uses authors as evidence for your claim |
| Little of your own voice | Your argument leads; sources support |
| No clear thesis | A thesis that answers the prompt |
Argumentative and Explanatory Synthesis
Synthesis essays come in two main forms. Check the prompt wording to see which you need.
- Argumentative synthesis: takes a position on a debatable issue and uses sources to support it, while addressing opposing views. The AP Language synthesis essay is this type.
- Explanatory synthesis: explains a topic by organising information from sources, without arguing for a position. It is common in introductory university courses.
Even an explanatory synthesis needs a controlling idea, such as the main factors behind an issue, so the essay has a clear direction.
Plan with a Source Grid
A grid helps you see connections across sources before you write. List sources down the side and the main points across the top.
| Source | Position | Key evidence | Supports which point? |
|---|---|---|---|
| Source A: city transport report | For congestion pricing | Traffic fell after pricing began | Point 1: reduces congestion |
| Source B: economist's article | For, with conditions | Revenue funds public transport | Point 2: funds alternatives |
| Source C: small business survey | Against | Owners fear lost customers | Counterargument |
| Source D: equity study | Mixed | Charges weigh more on low incomes | Point 3: needs discounts |
Once the grid is full, read across the "point" column. Points supported by two or more sources become body paragraphs. The sources here are illustrative.
Also note which sources disagree. Tension between sources is useful: it gives you a counterargument to address and shows the marker you read critically.
Write a Synthesis Thesis
Your thesis should answer the prompt with a clear position and hint at the reasons. It should come from your thinking about the sources, not from any single source.
Weak: There are many views on congestion pricing.
Strong: Cities should adopt congestion pricing, but only if the revenue funds better public transport and low-income drivers receive discounts, because the policy reduces traffic most fairly when it gives people real alternatives.
The strong thesis takes a position, adds a qualification and shows the essay's structure. Qualified theses like this are often more persuasive than absolute ones.
Structure of a Synthesis Body Paragraph
- Claim: a topic sentence stating your point, in your own words.
- Evidence from sources: two or more sources, paraphrased or briefly quoted, and cited.
- Commentary: explanation of how the evidence supports your claim and how the sources relate.
- Link: a sentence connecting the point back to the thesis.
Congestion pricing works best when it funds the alternatives it asks drivers to use. The city report shows traffic in the charging zone fell noticeably after pricing began (Source A), but the economist warns that such gains fade unless revenue improves buses and trains (Source B). Read together, the two sources suggest that the charge itself only starts the change; reinvestment sustains it. A pricing scheme without that commitment risks being seen as a tax rather than a transport policy.
Notice that the paragraph opens with the writer's claim, uses two sources together and spends as many words on commentary as on evidence.
Synthesis Essay Outline
| Section | Content |
|---|---|
| Introduction | Context for the issue, why it matters, thesis |
| Body 1 | First reason, supported by two or more sources |
| Body 2 | Second reason, supported by two or more sources |
| Body 3 | Counterargument from the sources, and your response |
| Conclusion | Restated position, wider implications |
For longer university synthesis essays, add body paragraphs for each additional point rather than making existing paragraphs longer.
Writing the Introduction and Conclusion
The introduction sets up the issue, shows that reasonable people disagree and ends with your thesis. Keep it short, so most of your time goes into the body.
Example introduction: As traffic grows in city centres, several cities have begun charging drivers to enter their busiest streets. Supporters point to cleaner air and faster journeys, while critics argue that the charges punish people who have no other way to travel. Cities should adopt congestion pricing, but only if the revenue funds better public transport and low-income drivers receive discounts, because the policy reduces traffic most fairly when it gives people real alternatives.
The conclusion restates your position in fresh words and shows what the sources add up to together. You might end with an implication, such as what a city should do first, or with a question the sources leave open.
Avoid introducing a new source in the conclusion. If a source matters, it belongs in a body paragraph where you can explain it.
Tips for the AP Language Synthesis Essay
On the AP English Language and Composition exam, the synthesis question gives you a prompt and a set of sources, usually around six or seven, including at least one visual. You need to use at least three of them.
- Reading time: the free-response section includes a 15-minute reading period; spend it reading the sources and filling a quick grid.
- Writing time: about 40 minutes is suggested for the synthesis essay.
- Citing: refer to sources by their letter or author, such as (Source A).
- Scoring: the six-point rubric awards a point for thesis, up to four for evidence and commentary, and one for sophistication.
- Commentary: most points come from explaining evidence, so do not just string sources together.
Check the current College Board course description for the latest exam details before your test.
Common Mistakes to Avoid
- Source-by-source paragraphs: organise by idea instead.
- Letting sources argue for you: your claim should lead every paragraph.
- Using one source per paragraph: synthesis means combining at least two.
- Ignoring opposing sources: addressing them makes your argument stronger.
- Too little commentary: explain every piece of evidence.
- Missing citations: cite every source you use, even when paraphrasing.
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Frequently Asked Questions
An essay that combines ideas from several sources to support your own thesis about an issue, organised by idea rather than by source.
It depends on the task. On the AP Language exam, you use at least three of the sources provided. University essays follow the brief.
A synthesis essay is built specifically around a set of sources and how they relate. An argumentative essay may use any evidence you find.
Commonly five: introduction, two or three body paragraphs and a conclusion. Longer essays add paragraphs per point.
In the AP exam, by source letter or author. At university, use your required citation style.
Yes, and you should. Addressing an opposing source and responding to it strengthens your argument.
Introduce the issue and why it matters, briefly show the debate, then end the introduction with your thesis.
Yes, as long as the sources remain central. Your own examples can add depth, but the task is to show how the sources relate.
Mostly paraphrase, with short quotations only where the exact wording matters. Paraphrase makes it easier to combine sources in one sentence.