How to Write a Synthesis Essay

A synthesis essay combines information and ideas from several sources to support a position or explain a topic. The skill is not summarising each source, but putting them in conversation with one another to build your own argument.

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Updated 21 October 2026 · EssayWriting.com editorial team

Key takeaways

A synthesis essay combines several sources to support your own position.
Organise by idea, not by source.
Summary restates one source; synthesis connects several.

Summary vs synthesis

Summary	Synthesis
Explains what one source says	Connects what several sources say
Organised source by source	Organised by idea or argument
Restates	Compares, contrasts, combines and evaluates
"Source A says... Source B says..."	"While A and B agree that..., C complicates this by..."

Types of synthesis essay

Argumentative synthesis: takes a position and uses sources as evidence (the AP Language format).
Explanatory synthesis: explains a topic by drawing information from several sources without arguing a position.
Literature review: a research-paper form of synthesis that maps what scholars have found on a question.

Step 1: read the sources actively

For each source, note the author's main claim, the evidence used, the perspective or bias, and one quotation or data point you might use. A simple grid helps:

Source	Main claim	Key evidence	Perspective	Agrees or disagrees with
A
B
C

Step 2: group sources by idea

Look for themes, agreements and disagreements. Each theme or point of tension can become a body paragraph. A strong synthesis paragraph usually draws on at least two sources.

Step 3: write your thesis

Weak: "The sources show different views about school start times."

Strong: "Although later start times create real transport and scheduling costs, the combined evidence on adolescent sleep, attendance and safety shows that districts should move high school start times to 8:30am or later."

The strong thesis takes a position and signals that it will weigh competing evidence.

Synthesis essay outline

Introduction: context for the issue, thesis.
Body 1: first reason, supported by two or more sources in conversation.
Body 2: second reason, same approach.
Body 3: counterargument drawn from a source, and your response.
Conclusion: how the evidence together supports your position and why it matters.

Build it with guiding questions in the essay outline builder.

Example synthesis paragraph

Later start times appear to benefit students most through sleep. Source A, a summary of adolescent sleep research, explains that teenagers' body clocks shift later during puberty, and Source C reports that students in a district that delayed its start time slept longer on school nights. Together, these sources suggest that early start times conflict with biology rather than with student discipline. Source D, however, notes that later dismissal can cut into after-school jobs, a cost that districts would need to address through scheduling.

Illustrative paragraph; the sources described are hypothetical.

Notice the verbs that connect sources: suggest, together, however, reports, explains. Your voice controls the paragraph; sources support it.

Synthesis on the AP English Language exam

The AP English Language and Composition exam's synthesis question gives you a set of sources on a topic and asks you to write an argument that incorporates evidence from at least three of them. Practical tips:

Read the prompt first, then skim all sources before choosing.
Take a position quickly and write a defensible thesis.
Use at least three sources, more if they help, and cite them as the prompt instructs (for example "Source A" or by author).
Explain how each piece of evidence supports your argument; do not just drop in quotations.
Check the current College Board scoring guidelines for exact requirements.

Synthesis sentence starters

"Both A and B argue that..., but they disagree about..."
"A's findings support B's claim that..."
"While A emphasises..., C points to..."
"Taken together, these sources suggest..."
"A's evidence complicates B's conclusion because..."

Common mistakes

Writing one paragraph per source (that is summary, not synthesis).
Letting sources do the arguing instead of your own analysis.
Using only sources that agree with you.
Quoting at length without explanation.
Forgetting to cite sources correctly.

Synthesis essay checklist

The thesis takes a clear position on the issue.
Paragraphs are organised by idea, not by source.
Most body paragraphs use at least two sources.
Your analysis connects and evaluates the sources.
A counterargument from the sources is addressed.
All sources are cited as required.

Related essay writing guides

Quick answers to common questions

Can I bring in outside sources?

In AP exams you should focus on the provided sources, though brief relevant knowledge can support your argument. In coursework, follow the brief.

How do I choose which sources to use?

Pick sources that offer the strongest evidence, different perspectives and at least one counterargument you can address.

How long is a synthesis essay?

It depends on the task. Coursework synthesis essays are often 1,000 to 2,500 words; exam essays are shorter.

Frequently asked questions

What is a synthesis essay?

An essay that combines ideas and evidence from several sources to support a position or explain a topic, organised by idea rather than by source.

How many sources does a synthesis essay need?

It depends on the assignment. The AP English Language synthesis question asks you to use at least three of the provided sources.

What is the difference between summary and synthesis?

A summary restates one source; synthesis connects several sources to build your own argument.

How do I cite sources in an AP synthesis essay?

Follow the prompt, which typically allows you to refer to sources by letter (Source A) or by author or title.

Helpful tools for this task

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