You’ve found twenty sources for your research. Your professor says you need to submit an annotated bibliography. You reach for your citation handbook — and immediately hit a wall. MLA uses a “Works Cited” title and a one-inch annotation indent. Chicago calls it a “Bibliography” and uses a half-inch indent. You’re not even sure which Chicago system your professor wants.
That’s exactly where most students get stuck. The difference between MLA and Chicago annotated bibliographies isn’t just about citation format — it affects your title, your spacing, your annotation paragraph layout, and even the terminology you use throughout the document.
Here’s how to build an annotated bibliography in both styles correctly, with a direct comparison so you can switch between them without second-guessing.
- MLA 9th Edition uses “Works Cited” as the title, double-spaces the entire document, and indents the annotation paragraph one inch from the left margin
- Chicago Style uses “Bibliography” as the title, and depending on your instructor’s preference, either single-spaces or double-spaces entries with a half-inch annotation indent
- Chicago has two systems: Notes-Bibliography (preferred in humanities) and Author-Date (common in sciences) — always check which one your professor requires
- The annotation itself is always one paragraph after the citation, but the indentation, spacing, and title conventions differ significantly between the two styles
- Both styles require alphabetical ordering and a hanging indent on the citation itself
What Is an Annotated Bibliography (and What It Isn’t)?
An annotated bibliography is a list of sources — books, journal articles, database entries, or other academic materials — arranged alphabetically. Each entry consists of two parts:
- A citation formatted in the required citation style (MLA, Chicago, APA, etc.)
- A summary annotation — a brief paragraph (usually 4 to 6 sentences, or about 150 to 250 words) that summarizes the source’s main argument and often evaluates its credibility and relevance to your research
You use an annotated bibliography when:
- Your professor assigns it as a standalone task
- You’re building a literature review and need to catalog sources before writing
- You’re preparing for a comprehensive exam or qualifying paper
- Your grant or thesis proposal requires a preliminary source review
You don’t need an annotated bibliography if your professor asks for a literature review instead. The key difference is structural: a literature review weaves sources together into continuous prose that develops a narrative about the field. An annotated bibliography lists sources separately, each followed by its own isolated annotation paragraph.
MLA 9th Edition Annotated Bibliography: Complete Formatting Guide
MLA 9th Edition is the standard citation style in the humanities — literature, arts, philosophy, cultural studies, and most language disciplines. The Modern Language Association’s Handbook (9th ed., section 5.132) provides the specific formatting rules for annotated bibliographies.
MLA Formatting Rules
Title: Center the title “Works Cited” at the top of the first page. Do not italicize, bold, or place it in quotation marks. It is simply the label for the section.
Citation format: Follow the standard MLA Works Cited format. Capitalize only the first word of the title and the first word after a colon in article titles. Italicize book titles, journal names, and container titles. Place the publication date near the end of the citation entry.
Hanging indent: The citation starts with a 0.5-inch hanging indent — the first line of the citation is flush left, and all subsequent lines in the citation are indented 0.5 inches.
Annotation indent: This is where students make the biggest error. The annotation paragraph begins on the line after the citation and is indented one full inch from the left margin. If the annotation spans multiple paragraphs, indent the first line of every paragraph after the first one as well.
Spacing: Double-space the entire document — between citations, within citations, and within the annotation itself. Unlike APA or Chicago, there are no extra blank lines between entries.
MLA Example
Smith, John. The History of Folklore. London: Routledge, 2018.
Smith’s book provides a thorough examination of the major roles filled by the numerous pagan goddesses of Northern Europe in everyday life, including their roles in hunting, agriculture, domestic arts like weaving, the household, and death. The author discusses relevant archaeological evidence, patterns of symbol and ritual, and previous research. The book includes a number of black and white photographs of relevant artifacts. This source is useful for understanding the mythological underpinnings of European folk narratives and the archaeological methods used to trace their origins.
Breaking down the MLA example:
- Citation: Author (Last Name, First Name). Italicized Title. City: Publisher, Year.
- Annotation indent: The entire annotation paragraph starts exactly one inch from the left margin — you can verify this by using the tab key twice (two half-inch tabs = one inch).
- Annotation content: Describes the book’s scope (thorough examination of pagan goddesses), notes the methods used (archaeological evidence, symbol and ritual patterns), and states relevance to research.
- Spacing: Double-spaced throughout, including between the citation and the annotation.
MLA Common Mistakes to Avoid
- Don’t italicize the title “Works Cited.” It’s a section label, not a title.
- Don’t use a half-inch indent for the annotation. The MLA handbook specifically requires a one-inch indent. This is the single most common formatting error students make.
- Don’t add blank lines between entries. MLA double-spaces everything uniformly.
- Don’t alphabetize by author first name. MLA alphabetizes by last name.
- Don’t summarize without evaluating. A strong annotation includes both a summary and a brief assessment of the source’s credibility or relevance.
Chicago Style Annotated Bibliography: Complete Formatting Guide
Chicago style, as outlined in the Chicago Manual of Style (18th ed., sections 13.68 and 13.69), is the dominant citation system in history, social sciences, and many graduate programs. It offers two distinct approaches, and students frequently mix them up without realizing it.
Chicago Notes-Bibliography System (Preferred in Humanities)
This is the system used when sources are cited in numbered footnotes or endnotes within the text. It’s the traditional format for history, literature, and most humanities disciplines.
Title: Center “Bibliography” at the top of the page.
Citation format: Author’s full name (not reversed). Italicize book titles. Use commas to separate citation elements. Include the city of publication for books — something MLA drops entirely.
Annotation options: Chicago gives you two choices:
- Same-line annotation: Place the annotation directly after the citation, without starting a new paragraph. You may use brackets to distinguish it.
- New-line annotation: Start the annotation on the next line. If you indent it, the annotation should begin at 0.5 inches — aligned with the start of the citation’s hanging indent.
Spacing: The Chicago Manual of Style allows single-spacing within entries with a blank line between entries. However, many professors require double-spacing for readability, so always check your assignment instructions.
Annotation indent: 0.5 inches (one tab stop). This is the critical difference from MLA’s one-inch indent.
Chicago Author-Date System (Common in Sciences and Social Sciences)
The Author-Date system places parenthetical citations in the text (e.g., Smith 2018) rather than footnotes. It’s more common in the social sciences and some graduate programs.
Title: “Bibliography” remains the standard title.
Citation format: Similar to APA format. The year of publication appears immediately after the author’s name — this is the key structural difference from Notes-Bibliography format.
Annotation: Follows the same options as Notes-Bibliography (same-line or new-line). The 0.5-inch indent rule applies equally.
Chicago Example (Notes-Bibliography System)
Battle, Ken. Child Poverty: The Evolution and Impact of Child Benefits. In K. Covell and R. B. Howe, eds., A Question of Commitment: Children’s Rights in Canada. Wilfred Laurier University Press, 2007.
Ken Battle draws on close study of government documents, as well as his own research as an extensively published policy analyst, to explain Canadian child benefit programs. He outlines some fundamental assumptions supporting the belief that all society members should contribute to the upbringing of children. His comparison of child poverty rates in a number of countries is a useful wake-up to anyone assuming Canadian society is doing a good job of protecting children. Battle pays particular attention to the National Child Benefit, arguing that it did not deserve to be criticized by politicians and journalists. However, he relies too heavily on his own work; he is the sole or primary author of almost half the sources in his bibliography. Still, Battle does offer a valuable source for this essay.
Breaking down the Chicago example:
- Citation: Author (Full Name). Title. In Editor Names, eds., Container Title. Publisher, Year.
- City of publication: Included for books (Wilfred Laurier University Press location would appear if required by your professor).
- Annotation indent: 0.5 inches — the annotation starts one tab stop left from the margin.
- Annotation content: Summarizes the book’s scope, notes the author’s credentials as a policy analyst, identifies strengths (comparison of international rates), and provides a critical evaluation (overuses own sources).
Chicago Common Mistakes to Avoid
- Don’t mix the two Chicago systems. The Notes-Bibliography and Author-Date formats have different citation structures. Pick one and stick with it.
- Don’t use a one-inch annotation indent. Chicago requires 0.5 inches, not one inch. Using MLA’s one-inch rule in a Chicago document will lose you formatting points.
- Don’t omit the city of publication when your professor requires the Notes-Bibliography system.
- Don’t assume Chicago always uses single-spacing. While the Manual permits it, many professors require double-spacing. Check your assignment sheet.
- Don’t confuse “Bibliography” with “References.” “References” is APA terminology. Chicago uses “Bibliography” (or “Works Cited” only in rare interdisciplinary cases).
Side-by-Side Comparison: MLA vs Chicago Annotated Bibliography
Here’s a direct comparison of the most important formatting differences. Keep this table handy while you’re building your bibliography.
| Feature |
MLA 9th Edition |
Chicago Style |
| List Title |
“Works Cited” (centered) |
“Bibliography” (centered) |
| Disciplines |
Humanities, literature, arts, philosophy |
History, social sciences, many graduate programs |
| Citation Name Order |
Author’s last name, first name |
Full first name (not reversed) |
| Annotation Indent |
One inch from left margin |
0.5 inches from left margin |
| Spacing |
Double-spaced throughout |
Single or double-spaced (check professor preference) |
| Blank Lines |
None between entries |
Optional blank line between entries |
| Hanging Indent |
0.5 inches on citation |
0.5 inches on citation |
| Citation Elements |
Author. Title. Publisher, Year. |
Author. Title. City: Publisher, Year. |
| In-Text Citation |
(Author Page#) |
Footnote or endnote (Notes-Bibliography) or (Author Year) (Author-Date) |
The One-Inch vs Half-Inch Rule
This is the single biggest reason students mess up annotated bibliographies. MLA requires the entire annotation paragraph to start exactly one inch from the left margin. Chicago requires it to start 0.5 inches from the left margin. You can verify this by pressing the tab key:
- MLA: Press Tab twice for a one-inch indent
- Chicago: Press Tab once for a half-inch indent
If your professor hasn’t specified which style to use, ask. The difference isn’t cosmetic — it affects every single entry you write.
The Annotation Itself: What’s the Same in Both Styles?
Despite their formatting differences, both MLA and Chicago agree on what the annotation should contain:
- Summary of the source’s main argument or thesis
- Scope of what the source covers
- Author credentials (when relevant and verifiable)
- Evaluation of the source’s credibility and usefulness
- Application to your own research question
Whether you write one paragraph or two per annotation, both styles expect you to be concise. Aim for 150 to 250 words per entry. Anything longer than that usually means you’re describing too much rather than analyzing.
Step-by-Step: Building Your Annotated Bibliography
Step 1: Identify the Required Citation Style
Before writing a single word, confirm whether your professor wants MLA 9th Edition or Chicago (and if Chicago, which system). If you submit the wrong format, your instructor can deduct points before reading your annotations.
Step 2: Gather Your Sources
Use academic databases (JSTOR, Web of Science, your university library catalog) to find peer-reviewed sources. Don’t rely on Wikipedia, general encyclopedias, or unverified websites unless your professor allows them. Check the guide on evaluating academic sources for tips on vetting sources.
Step 3: Create Citations
Use a citation management tool like Zotero to generate citations. Set your output style to MLA or Chicago before exporting — switching styles after generating citations often produces formatting errors.
Step 4: Write the Annotation
For each citation, write a paragraph that covers:
- What the source argues or reports
- Who the author is and why they’re qualified
- How the source contributes to your topic
- Why it matters for your research question
A useful formula: “This source examines [topic]. The author argues that [thesis]. The methodology/approach is [brief description]. This is relevant to my research because [connection].”
Step 5: Format Consistently
Apply the correct indentation rules, spacing, and title. Check every entry against the style rules above. One inconsistent entry can throw the entire bibliography off.
Step 6: Alphabetize
Both styles require alphabetical ordering by author last name. Double-check the order before submitting. If two works have the same author, alphabetize by title.
Annotation Writing: Three Types You May Need
Depending on your assignment, your professor may want different types of annotations. The University of Alberta library guide categorizes them clearly:
Descriptive Annotation
A straightforward summary of the source’s content without critical evaluation. You describe what the source covers, what arguments it makes, and what evidence it uses. These are common when your professor simply wants to see that you’ve read and understood the source.
Evaluative Annotation
A critical assessment of the source’s quality, methodology, and reliability. You compare the source’s findings with other works, assess its credibility, evaluate its methods, and determine whether its conclusions are justified. This is the type most professors want for graduate-level work.
Combined Annotation
A summary followed by a critical evaluation and a note about how the source applies to your research. This is the most common format for undergraduate annotated bibliographies and the most useful overall because it shows both understanding and judgment.
How to Choose Between MLA and Chicago
You don’t choose — your professor or department requires one. But here’s a practical guide to knowing which style is standard in your discipline:
| Discipline |
Typically Required |
| English Literature |
MLA 9th Edition |
| Humanities (Philosophy, Religious Studies, History of Art) |
MLA 9th Edition or Chicago Notes-Bibliography |
| History |
Chicago Notes-Bibliography |
| Social Sciences (Sociology, Political Science, Psychology) |
APA 7th Edition or Chicago Author-Date |
| Sciences |
APA 7th Edition |
| Graduate Programs (most) |
Chicago Notes-Bibliography |
| Education |
APA 7th Edition |
If you’re unsure, ask. Most professors are happy to specify upfront rather than grading you down for using the wrong system.
Frequently Asked Questions
Can I mix MLA and Chicago formatting in the same bibliography?
No. Pick one style and use it consistently throughout the entire document. Mixing formats is one of the fastest ways to lose formatting points.
How many sources should I include?
Your professor’s assignment sheet will specify a minimum or range. As a general rule, annotated bibliographies range from 10 to 25 entries. Don’t include sources just to pad the count — each entry should be relevant to your research topic.
What if my professor gives conflicting instructions?
Some professors say “MLA or Chicago style” without specifying which one. When this happens, choose the style most common in your discipline. If you’re still unsure, ask for clarification.
Do I need an introductory paragraph?
Neither the MLA handbook nor the Chicago Manual requires an introductory paragraph. However, some professors prefer one. Check your assignment sheet.
Common Mistakes Students Make (and How to Avoid Them)
Mistake 1: Wrong Annotation Indent
The problem: Using MLA’s one-inch indent for Chicago, or Chicago’s half-inch indent for MLA.
The fix: Memorize the rule for your assigned style. One inch for MLA (press Tab twice). Half inch for Chicago (press Tab once).
Mistake 2: Mixing the Two Chicago Systems
The problem: Writing the citation in Notes-Bibliography format but using Author-Date in-text citations, or vice versa.
The fix: Decide which Chicago system your professor requires and stick with it. The citation structure differs significantly between the two.
Mistake 3: Writing Too Much or Too Little
The problem: Annotations that are either a single sentence or four paragraphs.
The fix: Aim for one paragraph, 4 to 6 sentences, 150 to 250 words. This is the sweet spot professors expect.
Mistake 4: Skipping the Evaluation
The problem: Writing only a summary without any critical assessment.
The fix: Always include at least one evaluative sentence about the source’s credibility, methodology, or relevance to your research.
Mistake 5: Forgetting to Alphabetize
The problem: Listing sources in the order they were read rather than alphabetically by author.
The fix: Sort your bibliography by author last name before submitting. Use a spreadsheet or citation manager to help.
Your Next Steps After Building the Bibliography
Once your annotated bibliography is complete, the next logical step depends on what you’re working toward. If you’re writing a literature review, you’ll need to synthesize your sources into thematic sections rather than maintaining a list format — see the literature review synthesis matrix guide for that next phase. If you’re preparing a research proposal, you’ll move into writing the methodology section — check the research proposal methodology guide for the next step.
Writing an annotated bibliography is the foundation of good research. Get the formatting right, write thoughtful annotations, and you’ll set yourself up for a smooth literature review process.
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