How to Write the AP Lang Synthesis Essay: Plan, Structure and Common Mistakes

The synthesis essay gives you a set of short sources on a debatable issue and asks you to write your own argument, drawing on at least three of them. The trap is in the word "synthesis": the readers want your argument supported by sources, not a tour of what each source says.

Use the reading period well

The free-response section opens with a 15-minute reading period. Spend most of it on the synthesis sources:

• Read the prompt twice and underline exactly what it asks you to argue about.
• Skim each source, noting its main claim in a few words and whether it supports, opposes or complicates the issue.
• Look closely at the visual or data source; students often skip it, and it can provide strong, specific evidence.
• Mark the three or four sources you'll use and a position you can defend.

Take a clear position

Your thesis should answer the prompt directly and preview your reasoning. A qualified position, one that agrees under certain conditions or recognizes a trade-off, often leads to more sophisticated writing than a flat "yes" or "no," but only if you can support it.

Weak: "There are many views on public libraries."
Stronger: "Public libraries remain essential because they provide free internet access and safe community space, though their value depends on adapting services to how residents now read and work."

A reliable structure

1. Introduction: one or two sentences of context, then your thesis.
2. Two or three body paragraphs: each built around a reason that supports your thesis, not around a source.
3. Within each paragraph: claim → evidence from one or two sources → commentary explaining how that evidence proves your point.
4. Brief conclusion: extend the argument; show why it matters.

Cite sources correctly

Refer to sources by their letter or author, for example "(Source C)" or "according to the city budget report (Source D)." You must use at least three to meet the evidence requirement. Using a source to make a point and then explaining its limits is a good way to show critical thinking.

Commentary is where points are earned

The evidence-and-commentary row of the rubric is worth up to 4 of 6 points. Commentary means explaining why the evidence supports your reasoning. After every quote or statistic, ask: "So what?" and answer it in your own words. A paragraph that strings together three quotes with no explanation will score low even if the quotes are well chosen.

Common mistakes

• Summarizing each source in turn ("Source A says… Source B says…").
• Using only one or two sources.
• Copying long quotations instead of short, precise phrases.
• Ignoring the counterargument entirely; even one sentence acknowledging an opposing view can strengthen your reasoning.
• Running out of time; leave this essay at about 40 minutes so the other two get their share.

Practice

The College Board publishes past synthesis prompts with sample responses and scoring commentary on AP Central. Score your practice essays with the rubric, then use the AP Lang score calculator to see how your essay scores combine with your multiple-choice results. The rubric rows are explained in AP Lang rubric explained.

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