Chicago Author–Date Style Guide (17th Edition)

📘 When to Use the Author–Date System

The Chicago Author–Date style is one of two citation systems outlined in the Chicago Manual of Style . It's typically used in:

• Science and technology fields
• Social sciences (e.g. economics, sociology, political science)
• Environmental and health disciplines

🔄 How It Differs from Notes & Bibliography Style

• Author–Date: In-text citations use parentheses — e.g. (Smith 2020)
• Notes & Bibliography: Uses numbered footnotes with full citations at the bottom of the page
• Both styles include a full list of sources at the end (called “References” in Author–Date, “Bibliography” in Notes & Bibliography)

If you're writing in the sciences or social sciences and your guidelines specify “Chicago Style,” you're likely expected to use the Author–Date system.

📝 In-Text Citations in Author–Date Style

In the Chicago Author–Date system, citations appear directly in the text using parentheses. Each citation includes the author's last name, the year of publication, and, if needed, a page number.

✅ Basic Format

(Smith 2021)
(Smith 2021, 45)

👥 Multiple Authors

• Two authors: (Lee and Chan 2022)
• Three or more authors: (Garcia et al. 2020)

📑 Quoting vs Paraphrasing

• Direct quote: Include the page number — e.g. (Walker 2019, 142)
• Paraphrase: Page number is optional — e.g. (Walker 2019)

❓ Special Cases

• Same author, multiple works: Add the year to distinguish — e.g. (Taylor 2020) vs (Taylor 2022)
• Multiple sources in one citation: Separate with semicolons — e.g. (Smith 2020; Johnson 2018)
• No author: Use the title (shortened) in italics or quotation marks — e.g. ( Climate Change Report 2023)

Every in-text citation should correspond to a full reference in your “References” list at the end of your paper.

📖 Formatting the Reference List

In Chicago Author–Date style, all cited works appear in a reference list at the end of your paper. This section shows how to lay out your references correctly.

🧾 Layout & Style

• Title the page “References” , centred at the top.
• Alphabetise entries by the author’s last name .
• Use hanging indentation : the first line is flush left, and subsequent lines are indented 0.5 inches (1.27 cm).
• Single-space entries, with a blank line between them.
• Use sentence case for titles — capitalise only the first word and proper nouns.

🧱 General Format

Author Last Name, First Name. Year. Title of Work. Publisher. DOI or URL (if applicable).

📌 Example (Book)

Walker, Alice. 2003. The Color Purple. Mariner Books.

Make sure every in-text citation has a matching entry here — and that all reference list details (author names, years, titles) are consistent.

📚 Chicago Author–Date Citation Examples

Here are in-text and reference list examples for the most common source types:

📘 Book

In-text: (Walker 2003)

Walker, Alice. 2003. The Color Purple. Mariner Books.

📰 Journal Article

In-text: (Lee and Wong 2022)

Lee, Rachel, and James Wong. 2022. “Digital Learning Gaps in Higher Education.” Journal of Educational Research 45 (2): 115–130. https://doi.org/10.1234/edu.2022.045.

🌐 Website

In-text: (BBC News 2024)

BBC News. 2024. “Ocean Temperatures Reach Record Highs.” BBC News. May 14, 2024. https://www.bbc.com/news/environment-987654.

▶️ YouTube Video

In-text: (CrashCourse 2023)

CrashCourse. 2023. “What Is a Theory?” YouTube. March 2, 2023. https://www.youtube.com/watch?v=xyz123.

🖼️ Image or Figure

In-text: (NASA 2022)

NASA. 2022. Artemis I Launch. NASA Images. https://www.nasa.gov/images/artemis-launch.

Need more examples? Visit our Chicago examples page or use the Chicago Citation Generator .