An annotated bibliography is a list of sources where each citation is followed by a short paragraph, called an annotation, that summarizes and often evaluates the source. It looks like a normal reference list, but every entry does extra work: it tells the reader what the source is about and why it matters.
What is an annotated bibliography?
An annotated bibliography combines two things. First, a correctly formatted citation in a style such as APA or MLA. Second, an annotation of roughly 100 to 200 words placed directly under that citation. Instructors assign annotated bibliographies to help you read sources closely, compare them, and plan a research paper before you start writing it.
The annotation is not a quotation from the source and it is not a personal opinion essay. It is a compact, neutral account of what the source says, written in your own words. If you can explain a source in a few clear sentences, you understand it well enough to use it.
The structure of an entry
Each entry in an annotated bibliography has the same two parts in the same order:
- The citation. A full reference-list or works-cited entry, formatted in your assigned style. Entries are listed alphabetically by the author’s last name.
- The annotation. A short paragraph below the citation, usually indented, that describes the source and explains its relevance.
A complete annotation often answers four questions: What is the source about? Who wrote it and are they credible? How does it compare to your other sources? How will you use it in your own project? You do not need a separate sentence for each question, but together they make a strong annotation.
Types of annotations
There are two main types, and your assignment will usually tell you which one to write.
Descriptive (or informative) annotations
A descriptive annotation summarizes the content of the source. It explains the main argument, the topics covered, and the conclusions, without judging the quality of the work. Think of it as a fair, neutral abstract written by you.
Evaluative (or critical) annotations
An evaluative annotation does everything a descriptive one does, then adds an assessment. You judge the source’s reliability, its strengths and limits, the author’s authority, and how useful it is for your specific research question. Most college assignments ask for evaluative annotations because they show critical thinking.
How to write an annotated bibliography
Work through these steps for each source:
- Find and choose sources that are relevant to your topic and, where required, scholarly or peer reviewed.
- Read or skim each source carefully and take notes on the main argument and evidence.
- Write a full citation in your assigned style. A free citation generator can build the reference accurately so you can focus on the writing.
- Write the annotation in your own words. Start with a sentence on the main point, add a sentence or two of detail, then comment on quality and relevance if the assignment is evaluative.
- Keep each annotation roughly the same length, usually one paragraph of 100 to 200 words.
- Arrange all entries in alphabetical order by the first author’s last name.
If you are unsure how to format a particular source, our focused guides on how to cite a book, how to cite a journal article, and how to cite a website walk through each element.
APA annotated bibliography example
In APA 7th edition, the reference is formatted exactly as it would appear on a normal References page, with a hanging indent. The annotation goes on a new line below it and is indented as a block (about 0.5 inches). Use double spacing throughout. The example below is evaluative.
Smith, J. A. (2020). Reading strategies for academic success. University Press.
This book explains practical strategies that help students read scholarly texts more efficiently. Smith draws on classroom research to argue that active note taking improves comprehension and recall. The author is a recognized education researcher, which strengthens the work’s credibility. Compared with shorter study guides, this source offers deeper context and clear examples. It will support the section of my paper on study habits and provide a reliable scholarly foundation for that argument.
In-text: (Smith, 2020).
For full formatting rules, see our APA format guide or build entries with the APA citation generator. Note that APA uses an ampersand between authors in references and inside parentheses, and “and” in running text.
MLA annotated bibliography example
In MLA 9th edition, the citation follows Works Cited format, again with a hanging indent. The annotation begins on the next line, indented one inch from the margin so it lines up with the hanging indent of the citation. The example below is descriptive.
Smith, Jane A. Reading Strategies for Academic Success. University Press, 2020.
Smith presents a series of reading strategies designed for first-year college students. The book is organized by skill, moving from previewing a text to taking structured notes and reviewing material. Each chapter includes worked examples drawn from real courses. The work focuses on practical technique rather than theory, making it accessible to readers who are new to academic reading.
In-text: (Smith 14).
MLA spells out “and” between two authors and uses the author’s last name with a page number for in-text citations, with no comma. For details, read our MLA format guide or use the MLA citation generator. If you are choosing between styles, our APA vs MLA comparison explains the key differences.
Common mistakes to avoid
- Copying the abstract. The annotation must be in your own words, or it counts as plagiarism. See our guide on how to avoid plagiarism.
- Mismatched format. The citation and the rest of your paper must use the same style consistently.
- Listing entries out of order. Always arrange them alphabetically unless your instructor asks for a different order.
- Writing too much or too little. Aim for a balanced paragraph for every source.
Frequently asked questions
How long should each annotation be?
Most annotations are one paragraph of about 100 to 200 words. Descriptive annotations can be shorter, while evaluative ones tend to be longer because they include both a summary and an assessment. Always follow the length your instructor specifies.
What is the difference between an annotated bibliography and a reference list?
A reference list (APA) or Works Cited page (MLA) gives only the citations. An annotated bibliography adds a short paragraph under each citation that summarizes and often evaluates the source. For a fuller comparison, see our guide on works cited versus bibliography versus references.
Should I use descriptive or evaluative annotations?
Check your assignment. Descriptive annotations summarize what a source says. Evaluative annotations also judge its quality, credibility, and relevance to your project. College courses most often require evaluative annotations.
Do I alphabetize an annotated bibliography?
Yes. List entries in alphabetical order by the first author’s last name, exactly as you would in a normal reference list or Works Cited page. The annotations do not change this order.