Synthesis Essay
Also known as AP Lang synthesis essay
An essay that builds its own argument from several sources, putting them in conversation with each other instead of summarizing them one at a time.
- Summary
- Source A says parks cool cities. Source B says they cost money. Source C says people like them.
- Synthesis
- Parks cost money (Source B), but the heat they prevent (Source A) costs more, and residents already use them (Source C).
In practice
A synthesis essay builds an argument of its own from several sources. Instead of summarizing each source in turn, it puts them in conversation: one source supports a point, another complicates it, a third supplies the number that settles it. The writer's thesis is the thread that ties them together, and the sources serve that thesis.
Most students meet the form on the AP English Language and Composition exam, where the synthesis question is one of three free-response essays. Students read six short texts on a topic, including visual and quantitative sources such as charts, and write an argument that combines and cites at least three of them. The exam is digital, and the free-response section runs 2 hours and 15 minutes, including a 15-minute reading period.
Outside AP, synthesis is the skill behind a literature review, a research paper and a policy brief: reading what several people have said about a question and saying something none of them said alone. The difference between synthesis and summary is the difference between "Source A says" and "Source A and Source C agree on the cost, but only C accounts for who pays it."
Synthesis in a scene
INT. CITY HALL - MAYOR'S OFFICE - DAY
Three reports fanned across the desk. DEV (30s) taps each one as the MAYOR (60s) eats lunch.
DEV
Parks and Rec says a new park costs four million. The heat study says shade drops street temperature nine degrees.
He slides the third report over, open to a chart.
DEV
And the hospital says every heat wave costs us six million in ER visits. Avoiding two-thirds of those costs would cover the park’s price.
Opens as a new Plot project once you sign in or create a free account. Inkwell keeps this copy for 24 hours.
Dev doesn't read the reports aloud one by one. He links a cost, an effect and a second cost into one claim no single report makes. That linking is what a synthesis essay asks for.
Synthesis essay examples
AP-style prompt on public libraries: sources include a budget table, a librarian's essay, a survey of how people use libraries and a photo of a crowded reading room. A strong thesis might argue that libraries deserve more funding because they now serve as a town's free internet access, job center and cooling station, citing the survey and the budget together.
Prompt on standardized testing: sources include a college admissions study, a teacher interview, a graph of score trends and an op-ed. A synthesis essay could argue tests should be optional, using the study and graph to show what scores do and do not predict, and the op-ed as the view it answers.
Research paper on remote work: rather than one paragraph per article, each paragraph makes a claim (productivity, isolation, cost) and brings two or three studies to it, noting where they disagree and why.
How to write a synthesis essay
Read the prompt, then the sources, with a pencil. For each source, note its claim, its kind of evidence and its bias. On the AP exam, use the 15-minute reading period for this and do not start writing until you have a position.
Write a thesis that takes a side and could not come from any one source. "Cities should fund libraries as public infrastructure" is an argument; "Libraries have pros and cons" is not.
Plan body paragraphs around your reasons, not around the sources. Each paragraph should use at least two sources, say how they relate (agree, conflict, build on each other) and explain how they support the thesis.
Cite as you go, in the style the prompt asks for, such as (Source A) or the author's name. Answer at least one source that cuts against you, and end by saying what your argument means for the reader.
Synthesis vs. summary
A summary reports what one source says. A synthesis combines what several sources say to support a claim the writer makes. A paragraph that starts "Source A states" and ends with a quote is summary; a paragraph that starts with your claim and uses A and C as evidence is synthesis.
The easiest test is the topic sentence. If it names a source, the paragraph is probably organized around that source. If it names an idea, it is probably organized around your argument, which is what graders and readers are looking for.
Writing a synthesis essay thesis
A synthesis thesis has to do three jobs at once: answer the prompt, take a side and set up the way your sources will fit together. "Communities should treat public libraries as essential infrastructure, because they now provide internet access, job help and emergency shelter that no other public service covers" does all three. A reader can already guess which sources will support each reason.
Avoid a thesis that only lists the issue's sides or repeats the prompt. "There are many views on libraries" gives a grader nothing to measure. A qualified thesis, one that takes a side but names a limit, is often the strongest choice, because it shows you read the sources that disagree with you.
Test your thesis against the sources before you write. If only one source supports it, narrow it; if every source supports it without complication, it may be too obvious to argue.
Common questions
What is a synthesis essay?
An essay that makes its own argument by combining several sources, showing how they relate to each other and to the writer's thesis instead of summarizing them one at a time.
How many sources do you need in an AP Lang synthesis essay?
The AP English Language exam gives you six sources and asks you to cite at least three. Using more is fine if each one does work for your argument.
How do you start a synthesis essay?
With a sentence or two that frames the debate the sources are part of, followed by a thesis that takes a position none of the sources states on its own.
How long is the AP Lang synthesis essay?
There is no word limit. The three free-response essays share 2 hours and 15 minutes, including a 15-minute reading period, so most students spend about 40 minutes writing the synthesis essay.
What is the difference between synthesis and summary?
Summary restates what a source says. Synthesis connects several sources to make a point of your own, showing where they agree, conflict or build on each other.
Can a synthesis essay use outside sources?
On the AP exam the provided sources are the point, though a brief outside example can help. In a research paper, synthesis is built from whatever sources you find.
What is a good synthesis essay thesis?
One that takes a clear position on the prompt and could only come from reading the sources together, such as a claim that connects the cost in one source to the benefit in another.