Chicago Style Annotated Bibliography: Format, Annotations, and Examples

A Chicago-style annotated bibliography is an alphabetical list of sources formatted in Chicago citation style, each followed by a short paragraph called an annotation. Formatting each entry is a two-part job: build the citation, then write the annotation on a new line beneath it with matching indentation. 

This guide covers the two types of annotations and how to write each, how long they should run, the full formatting and organization rules for Chicago annotated bibliography, and worked examples to model.

Types of annotations

Your assignment determines what each annotation should include. The two main types are summary annotations and evaluative annotations.

A summary annotation describes the source’s central argument, scope, and main findings. It answers questions such as:

• What subject does the source examine?
• What argument does the author make?
• What evidence or research methods support that argument?
• What conclusions does the source reach?

An evaluative annotation includes a summary and an assessment of the source. It examines the author’s expertise, the quality of the evidence, the research methods, and the source’s relevance to your project.

Some assignments also require a reflection on how you will use the source. You might explain that it supplies historical background, supports a claim, introduces a useful method, or presents a competing interpretation.

Evaluative annotations are often the first step toward a bigger project. Here’s how an annotated bibliography vs literature review differs.

How to write an evaluative annotation?

An evaluative annotation connects a source’s argument to a reasoned judgment about its usefulness. Read the full source and take notes on the following:

1. Central claim: State the author’s main argument in your own words.
2. Author’s expertise: Identify qualifications or relevant experience that support the author’s authority.
3. Publication context: Establish whether the source is a scholarly article, book, government report, news story, or another type of publication.
4. Evidence and methods: Examine how the author collected, selected, and interpreted the evidence.
5. Currency: Assess whether the publication date suits your research question. Historical research often requires older primary sources.
6. Perspective: Identify assumptions, institutional interests, or theoretical commitments that shape the argument.
7. Strengths: Point to a specific feature, such as detailed archival research or a clearly explained method.
8. Limitations: Describe a specific constraint, such as a narrow sample, missing perspective, or limited geographic coverage.
9. Audience and purpose: Explain whom the source addresses and what it aims to accomplish.
10. Research use: State how the source will contribute to your paper.

Turn the points relevant to your assignment into a connected paragraph. Support judgments with details from the source. For example, explain which archival records an author uses and how those records support the book’s interpretation. Give readers enough information to understand the basis for your assessment.

How to write a summary annotation?

A summary annotation gives readers an accurate account of a source’s content. Use these steps:

1. Identify the subject and scope. Name the issue, population, location, or period the source covers.
2. State the central argument. Explain the author’s main claim in one clear sentence.
3. Describe the approach. Identify the evidence or method, such as interviews, experiments, archival documents, or textual analysis.
4. Report the main findings. Include the conclusions most relevant to your bibliography’s topic.
5. Check accuracy and wording. Compare your paragraph with the source and revise any wording that misrepresents the author’s position.

Write the annotation in your own words. Use the author’s last name to make attribution clear: “Cronon argues,” “the researchers find,” or “the report documents.” Direct quotations require quotation marks and a page number or another appropriate locator.

Keep a summary-only annotation focused on what the source says. Save judgments about its credibility and usefulness for assignments that request evaluation or reflection.

How long should annotations be?

Follow the word count in your assignment. Chicago style does not prescribe one annotation length for every bibliography.

If your instructor provides no length requirement, use 100–200 words per annotation as a practical drafting target. A short summary can fit into fewer words; an evaluation that addresses methods, limitations, and relevance needs more space. The examples below demonstrate concise annotations.

Count the annotation separately from the citation unless your assignment specifies a combined word count. Keep each sentence focused on the information readers need to understand or assess the source.

How to format an annotated bibliography in Chicago style?

Chicago has two citation systems: notes and bibliography and author-date. This guide’s examples use notes-and-bibliography entries, a common requirement in history and the humanities. Check your assignment before choosing a system.

The Chicago Manual of Style, 18th edition, was published in 2024. Turabian’s A Manual for Writers of Research Papers, Theses, and Dissertations adapts Chicago conventions for student papers. Although you should always follow the edition and the Chicago annotated bibliography format your professor has requested.

Citation style

Use bibliography entries for a notes-and-bibliography assignment. A basic book entry follows this pattern:

Last Name, First Name. Book Title: Subtitle. Publisher, Year.

Under Chicago’s 18th edition guidance, a book citation generally omits the place of publication.

An author-date assignment uses reference-list entries, with the publication year immediately after the author’s name:

Last Name, First Name. Year. Book Title: Subtitle. Publisher.

Citation entries

• Give complete publication details for every source.
• Invert the first author’s name: “Cronon, William.”
• Italicize book titles and journal titles.
• Put article titles, chapter titles, and webpage titles in quotation marks.
• Include a journal article’s full page range when available.
• For an online journal article, include its DOI in URL form when one is available.

Format

Follow your instructor’s document requirements. These layout suggestions provide a starting point for a student paper:

• Set 1-inch margins and use a readable font, such as 12-point Times New Roman.
• Center the heading Annotated Bibliography at the top of the page.
• Give each citation a 0.5-inch hanging indent. Its first line begins at the left margin, and subsequent lines are indented.
• Put the annotation on a new line beneath its citation.
• Indent the annotation paragraph 0.5 inch from the left margin.

Citation spacing and annotation spacing may differ. One possible layout uses single-spaced citations and annotations, with a blank line between entries. Treat this as a layout option. Student-paper assignments can require single-spaced citations with double-spaced annotations or double spacing throughout. Apply the spacing your instructor specifies.

Set hanging indents through your word processor’s paragraph settings. Use paragraph indentation settings for annotations as well, so the alignment remains consistent when text wraps onto another line.

Organization

Alphabetize entries by the first author’s last name. For a source credited to an organization, alphabetize by the organization’s name. When a source has no author, alphabetize by its title, ignoring an initial “A,” “An,” or “The.”

Chicago style annotated bibliography example

These Chicago annotated bibliography examples show summary and evaluative annotations for published sources. Apply the hanging indents and paragraph spacing described above in your document. Each annotation begins on a new line directly beneath its citation.

Example 1: Book with a summary annotation

Cronon, William. Changes in the Land: Indians, Colonists, and the Ecology of New England. Hill and Wang, 1983.

Cronon examines how Indigenous land-use practices and European colonization shaped New England’s environment. Drawing on historical accounts and ecological evidence, he connects changes in forests, wildlife, and agriculture to systems of property ownership and trade. The book explains how colonial settlement transformed relationships among people, land, and markets.

Example 2: Journal article with an evaluative annotation

Hardin, Garrett. “The Tragedy of the Commons.” Science 162, no. 3859 (1968): 1243–48. https://doi.org/10.1126/science.162.3859.1243.

Hardin argues that individuals pursuing their own interests can deplete a resource held in common. His hypothetical shared pasture illustrates how incentives can produce collective environmental harm. The article provides a clear conceptual model for discussing resource management, but its treatment of the commons gives limited attention to communities that establish and enforce shared rules. For a paper on environmental governance, it supplies an influential argument to examine alongside empirical studies of collectively managed resources.

Webpage citation pattern

For a webpage, record the author or organization, page title, website name when needed, publication or revision date, and URL. Include an access date when the page has no publication or revision date. Omit a repeated website name when it duplicates the organizational author.

The World Health Organization provides vaccine and immunization information through its https://www.who.int/immunization resource.

Build the citation from the page you actually consult:

World Health Organization. “[Exact Page Title].” Accessed [Month Day, Year]. [URL of the Page Consulted].

Replace every bracketed field with the page’s details. If the page supplies a publication or revision date, place that date after the title. In the annotation, identify the information you used, its intended audience, and its relevance to your research. For a page containing statistics, record the reporting period and the population or geographic area covered.