How to Write an Annotated Bibliography (With Examples)

An annotated bibliography is a list of sources (books, articles, websites, etc.) where each entry includes a full citation followed by a brief paragraph — the annotation — that summarizes, evaluates, and reflects on the source. Unlike a standard reference list or bibliography, which only provides publication details, an annotated bibliography requires you to engage critically with each source.

Instructors assign annotated bibliographies for several reasons: to help you develop research skills, to ensure you have found and read relevant sources before writing a paper, and to practice evaluating the quality and relevance of academic literature. They are commonly assigned in undergraduate courses across all disciplines and are a standard component of thesis and dissertation proposals.

Annotations generally fall into three categories, and your instructor may ask for one or a combination of them. Understanding the difference will help you write annotations that meet the assignment requirements.

• Summary annotations — describe what the source is about: the main argument, methodology, findings, and conclusions. This is the most common type and the minimum expected in most assignments.
• Evaluative annotations — assess the quality and credibility of the source: is the methodology sound? Is the author an expert? Are there limitations or biases? This type goes beyond summary to offer your critical assessment.
• Reflective annotations — explain how the source connects to your research question or thesis: does it support your argument, provide background context, or offer a counterpoint? This type demonstrates how you plan to use the source in your paper.

A good annotation is typically 100 to 200 words (about 4 to 6 sentences). It should be concise, specific, and written in your own words. Follow these steps for each source:

• Read the source thoroughly — do not annotate a source you have only skimmed
• Identify the main argument or purpose — what is the author trying to prove or explain?
• Note the methodology — how did the author reach their conclusions (experiment, survey, literary analysis, case study)?
• Evaluate the credibility — is the author qualified? Is the source peer-reviewed? Are there obvious biases?
• Connect to your research — explain how this source relates to your topic and whether you plan to use it

Write the annotation as a single paragraph (unless your instructor specifies otherwise). Use the third person and academic tone. Avoid starting every annotation with "This article..." — vary your sentence openings to keep the writing engaging.

In APA format, the citation comes first (formatted exactly as it would appear in a standard reference list), followed by the annotation paragraph indented to match the hanging indent of the citation.

Walker, M. (2017). Why we sleep: Unlocking the power of sleep and dreams. Scribner.

    Walker, a neuroscience professor at UC Berkeley, synthesizes decades of research on the effects of sleep on human health, cognition, and longevity. The book argues that sleep deprivation is a public health crisis with measurable impacts on memory, immune function, and emotional regulation. While written for a general audience rather than an academic one, the claims are well-supported by peer-reviewed studies cited throughout. This source provides foundational context for my research on the relationship between sleep habits and academic performance in university students.

In MLA format, the citation follows MLA Works Cited formatting rules. The annotation follows the citation as a new paragraph with standard indentation.

Walker, Matthew. Why We Sleep: Unlocking the Power of Sleep and Dreams. Scribner, 2017.

    Walker draws on his neuroscience research to argue that modern society undervalues sleep, with serious consequences for public health. The book covers the biological mechanisms of sleep, the cognitive effects of sleep deprivation, and the societal factors that contribute to insufficient sleep. Although the book targets a popular audience, its arguments are grounded in peer-reviewed research. This source is relevant to my paper because it establishes the scientific basis for linking sleep quality to academic outcomes.

• Writing a summary only — most assignments expect evaluation and reflection, not just a description of the source
• Making the annotation too short — a two-sentence annotation does not demonstrate engagement with the source; aim for 100 to 200 words
• Copying the abstract — an annotation should be in your own words and include your assessment, not a copy of the author's abstract
• Using first person excessively — while "I" is acceptable in reflective annotations, focus on the source rather than yourself
• Formatting the citation incorrectly — the citation portion must follow your required style (APA, MLA, Chicago) exactly
• Including sources you have not read — annotating a source you only skimmed will result in vague, generic descriptions that instructors can easily identify

An annotated bibliography is one of the few assignments where quality matters more than quantity. Five well-chosen, thoroughly annotated sources are more valuable than fifteen poorly annotated ones. Focus on finding sources that are directly relevant to your research question and that you can engage with critically.