How to Write an Annotated Bibliography (Formula + Example)
An annotated bibliography is a formatted list of sources where each citation is followed by a short paragraph — the annotation — that summarizes the source, evaluates its credibility, and states how you will use it. The three-move formula (summarize → evaluate → connect) fits almost every assignment; the formatting follows whichever citation style your class uses.
- Citation — full APA/MLA/Chicago entry, hanging indent
- Summarize (2–3 sentences) — question, findings, evidence
- Evaluate (1–2 sentences) — credibility, method, limits
- Connect (1 sentence) — the source’s job in your paper
1. Confirm the required flavor
Annotated bibliographies vary more than students expect: summary-only vs. evaluative annotations, 100 vs. 250 words, APA vs. MLA vs. Chicago, alphabetical vs. thematic order. Thirty seconds with the assignment sheet prevents redoing the whole thing.
2. Format the citation first, exactly
Each entry starts with a full citation in the required style — hanging indent included. Build it from the actual source in front of you, not from memory or from an AI suggestion: bibliography entries are graded on precision, and invented details are easy to spot.
3. Summarize in two or three sentences
What question does the source ask, what did it find, what evidence does it stand on? Write it in your own words without opinion — the summary proves you read past the abstract.
4. Evaluate credibility and limits
One or two sentences: peer-reviewed or not, sample size and method, author authority, notable bias or funding, and how current it is. "A 2019 survey of 40 students at one university" and "a meta-analysis across 200 schools" deserve different weight, and saying so is the point.
5. Connect it to your project
Close with the source’s job in your paper: which section it supports, what it proves, or which other source it argues with. This sentence turns the bibliography from busywork into your paper’s outline in disguise.
Twenge, J. M. (2020). Why increases in adolescent depression may be linked to the technological environment. Current Opinion in Psychology, 32, 89–94. — Twenge synthesizes survey data linking post-2012 rises in adolescent depression to smartphone-era social patterns, arguing the timing rules out purely economic explanations. As a single-author synthesis by a researcher known for this position, it is rigorous but contested — critics dispute the effect sizes. It anchors my paper’s "timing" argument and pairs with Orben & Przybylski (2019) as the strongest counter-source.
Mistakes that cost the most points
Annotating the abstract
Instructors can tell when an annotation paraphrases the abstract instead of the source — abstracts do not contain the limitations and details a real evaluation mentions.
All summary, no judgment
Unless the assignment says summary-only, an annotation without evaluation misses most of the available points. The evaluative sentence is where you demonstrate source literacy.
Unverified citation details
Wrong years, invented page ranges, misspelled journals — often the residue of citing from memory or from an AI answer. Every element of the citation should come from the source itself.
Writing this with AI in the mix
Annotated bibliographies are uniquely exposed to AI hallucination, because the failure mode is the assignment: models asked for "five sources on X, annotated" will happily produce plausible authors, real-sounding journals, and DOIs that resolve to nothing. Instructors know this, and many now spot-check bibliography entries as a matter of routine.
Verify every entry with the fake-citation checker before submission — it checks that DOIs resolve and sources exist. And if you drafted annotations with AI help, rewrite them in your own words; a bibliography where every annotation has the same synthetic rhythm reads as generated even before a detector confirms it.
Sentence-level scan — see what reads as AI before your grader does.
Rewrite flagged passages in a natural, human register.
Verify every reference is real — AI tools invent sources.
Frequently asked questions
How long should each annotation be?
Typically 100–200 words per source unless the assignment specifies otherwise: two or three sentences of summary, one or two of evaluation, one connecting it to your project.
What is the difference between APA and MLA annotated bibliographies?
Only the citation format and title conventions change — APA uses author–date citations and "References"-style entries; MLA uses author–page and "Works Cited" formatting. The annotation itself follows the same summarize–evaluate–connect structure in both.
Is an annotated bibliography alphabetical?
By default yes, alphabetized by author surname like a normal reference list. Some assignments group sources by theme instead — alphabetical within each theme — so check the sheet.