Best examples of Chicago style abbreviation examples for research papers

Quick examples of Chicago style abbreviation examples in action

Instead of starting with theory, let’s jump straight into a few real examples of Chicago style abbreviation examples you’re likely to use in a research paper:

• U.S. vs. United States

  • Text: U.S. foreign policy shifted after 1945.
  • Alternative: United States foreign policy shifted after 1945. (no abbreviation)
    Chicago allows both, but many academic writers spell out United States as a noun and use U.S. only as an adjective.

• Percent vs. %

  • Text: Only 12 percent of respondents answered the question.
    Chicago prefers percent in running text and % in tables and charts.

• BC / AD vs. BCE / CE

  • Text: The city was founded in 753 BC.
  • Alternative: The city was founded in 753 BCE.
    Chicago accepts both systems; many humanities departments now prefer BCE/CE.

These quick examples of Chicago style abbreviation examples show the pattern: Chicago usually favors spelling things out in the main text and saving heavy abbreviation for notes, tables, and technical material.

Core principles behind Chicago-style abbreviations

Before we get into more examples of Chicago style abbreviation examples, it helps to understand the logic Chicago uses.

Chicago Manual of Style, 17th edition (often called CMS 17), leans on three ideas:

• Spell it out on first use in most academic contexts, especially for organizations and technical terms.

  • Example: The World Health Organization (WHO) released new guidelines.
    After that, WHO is fine.

• Avoid unexplained abbreviations in the main text if they might confuse a general academic reader.
  Chicago is friendlier to abbreviations in footnotes, endnotes, and parenthetical citations.

• Follow common practice for widely recognized abbreviations: U.S., UK, PhD, DNA, NASA, etc.
  You don’t need to define NASA or FBI in most humanities papers.

For details, see the official Chicago guidance in chapters 10 and 14 of The Chicago Manual of Style (17th ed.). Many university writing centers, such as the University of Chicago Writing Program, echo these same rules.

Real examples of Chicago style abbreviation examples in the main text

Chicago is conservative about abbreviations in regular prose. Here are some of the best examples of Chicago style abbreviation examples you’ll actually see in student papers and journal articles.

Dates, eras, and time

• BC / AD and BCE / CE

  • The reforms of 27 BCE reshaped Roman governance.
  • The council met in AD 325.
    Chicago puts AD before the year (AD 325) and BC after the year (325 BC). For BCE/CE, both go after the year (27 BCE, 2024 CE).

• a.m. / p.m.

  • The meeting began at 9:30 a.m. and ended at 4:15 p.m.
    Chicago uses lowercase with periods and a space before the abbreviation.

• Centuries
  Chicago prefers spelled-out centuries in running text:

  • In the nineteenth century, industrialization accelerated.
    Use numerals (19th century) mainly in notes, tables, or when space is tight.

Geographic abbreviations

• U.S. / United States

  • As a noun: Immigration to the United States increased in the late nineteenth century.
  • As an adjective: U.S. immigration policy changed significantly.
    Chicago allows US without periods in some contexts, but U.S. with periods remains standard in many humanities journals.

• States and countries
  In the main text, Chicago prefers spelled-out state names:

  • She grew up in California, then moved to New York.
    Abbreviate states—CA, NY, TX—mainly in tables, notes, or postal addresses.

• Common organizations

  • According to the CDC, vaccination rates increased in 2023.
    The Centers for Disease Control and Prevention (CDC) is widely known, so many writers use CDC without spelling it out, especially in health and policy papers. For formal work, you can still spell it out on first mention.

For health-related research, Chicago style plays nicely with technical abbreviations commonly used by the CDC and NIH, as long as you define less familiar terms.

Examples of Chicago-style Latin abbreviations (and when to avoid them)

Latin abbreviations are one of the most confusing areas for students. Chicago has clear preferences, and trends in 2024–2025 are moving away from heavy Latin use in the main text.

e.g., i.e., etc., and friends

Chicago’s stance:

• e.g. (“for example”) and i.e. (“that is”)
  Chicago recommends using these mainly in parentheses, notes, and tables, not in running text.

  • Parenthetical: Many cities (e.g., Chicago, New York, and Los Angeles) expanded rapidly.
  • Footnote: For other examples, see Smith, 45–47 (e.g., case studies from Europe and Asia).

  In regular prose, Chicago prefers English equivalents:

  • For example, many cities such as Chicago, New York, and Los Angeles expanded rapidly.
  • That is, the data set excludes respondents under 18.

• etc.
  Chicago uses etc. sparingly and usually not with phrases like such as or for example (it becomes redundant).

  • Acceptable in a note: The archive holds letters, diaries, account books, etc.
    In the main text, Chicago encourages you to name the items or say and so on.

ibid., idem, and modern Chicago practice

Older Chicago-style papers were full of ibid. and idem in footnotes. The 17th edition changed direction:

• Ibid. is now discouraged.
  Chicago 17 prefers shortened notes:

  • First note: 1. John Smith, *Urban Politics (Boston: Beacon Press, 2018), 45.*
  • Later note: 5. Smith, *Urban Politics, 103.*

• Idem and similar Latin abbreviations are rarely used in current Chicago-style student work. Most universities in 2024–2025 expect students to follow the shortened-note system instead.

These are striking modern examples of Chicago style abbreviation examples evolving with time: the manual is actively moving away from Latin shortcuts in notes.

Examples of Chicago style abbreviation examples in notes and bibliography

Abbreviations show up most heavily in footnotes, endnotes, and bibliographies, especially in Chicago’s notes-and-bibliography system.

Common note abbreviations

Here are some real examples of Chicago style abbreviation examples you’ll see in notes:

• vol. / vols. for volume(s)

  • 2. Jane Doe, *Global Trade, 2nd ed., 3 vols. (New York: Routledge, 2020), 1:45.*

• ed. / eds. for editor(s) or edition

  • 3. Robert Brown, ed., *Voices of the Gilded Age (Chicago: University of Chicago Press, 2019), 79.*

• trans. for translator

  • 4. Max Weber, *The Protestant Ethic and the Spirit of Capitalism, trans. Talcott Parsons (New York: Scribner, 1958), 23.*

• n.d. for no date

  • 5. “Community Health Survey,” n.d., City Archives, Boston.

• para. for paragraph, often used with online sources without page numbers

  • 6. CDC, “COVID-19 Vaccination Trends,” last modified May 5, 2024, para. 4, https://www.cdc.gov/…

Chicago allows these abbreviations because notes and bibliographies prioritize compactness over conversational flow.

Journal and reference abbreviations

In bibliographies, you’ll also see:

• no. for issue number and vol. for volume

  • Smith, John. “Housing Policy in the 1970s.” *Journal of Urban History 42, no. 3 (2016): 201–230.*

• pp. for pages in some contexts, though Chicago often omits pp. in journal citations if the page range is clearly a page range.

• et al. for multiple authors in notes and in-text citations (for Chicago’s author-date system):

  • Johnson et al. (2022) argue that…
    Chicago usually spells out up to three authors before resorting to et al.

These bibliographic patterns are some of the most practical examples of Chicago style abbreviation examples you can reuse directly in your own references.

Academic and technical examples of Chicago style abbreviation examples

For research in science, medicine, or social science, Chicago’s author-date system often appears alongside highly technical abbreviations.

Academic degrees and titles

Chicago accepts common degree abbreviations in biographical notes and acknowledgments:

• Maria Lopez, PhD, is a professor of sociology at Harvard University.
• James Carter, MD, led the clinical trial.

Chicago typically omits periods in degree abbreviations like PhD, MA, BA, MD, following modern academic usage.

For titles, Chicago recommends avoiding titles like Dr. in the byline if the degree is already listed:

• Preferred: James Carter, MD
• Avoid: Dr. James Carter, MD

Scientific and medical abbreviations

In scientific writing that still follows Chicago, you’ll see:

• DNA, RNA, WHO, NIH used without explanation, since they are widely recognized.
  • NIH funding increased for mRNA research in 2021.
• Less common abbreviations should be spelled out on first use:
  • The randomized controlled trial (RCT) included 500 participants.
    
    Later: The RCT results supported the hypothesis.

When you cite health sources such as the Mayo Clinic or WebMD, follow their technical abbreviations but still define them for a general academic audience.

These scientific abbreviations are another set of examples of Chicago style abbreviation examples that show how the style adapts to specialized fields while keeping readers oriented.

Style choices and 2024–2025 trends in Chicago abbreviations

A few patterns have become more common in Chicago-style writing over the last few years:

• Less Latin in the main text.
  Many journals now prefer for example over e.g. and that is over i.e., especially outside parentheses.

• More spelled-out organization names in humanities papers.
  Instead of writing UN on first use, writers increasingly use United Nations (UN), then UN later.

• Flexible treatment of U.S. vs US.
  Some publishers drop the periods and use US; others stick with U.S.. Chicago allows both; follow your department or journal’s house style.

• Digital sources and paragraph numbers.
  With more online sources lacking stable page numbers, Chicago-style papers now rely more on abbreviations like para. or section headings in notes.

These evolving practices give you more modern examples of Chicago style abbreviation examples to model, especially if you’re writing for current journals or graduate programs.

Common mistakes with Chicago-style abbreviations (and better examples)

Here are some frequent errors students make—and better examples of Chicago style abbreviation examples that fix them.

• Error: Abbreviating in the main text without context

  • Weak: The WHO and CDC issued new guidelines.
  • Strong: The World Health Organization (WHO) and the Centers for Disease Control and Prevention (CDC) issued new guidelines.

• Error: Mixing Latin abbreviations with English phrases

  • Weak: For example, etc., many cities grew rapidly.
  • Strong: For example, many cities, including Chicago and New York, grew rapidly.

• Error: Overusing abbreviations in narrative history

  • Weak: In 19th c. Europe, indust. dev. reshaped soc.
  • Strong: In nineteenth-century Europe, industrial development reshaped society.

• Error: Using ibid. under Chicago 17

  • Weak: 3. Ibid., 56.
  • Strong: 3. Smith, *Urban Politics, 56.*

Each correction gives you a cleaner, more reader-friendly example of Chicago style abbreviation examples that will satisfy both your style guide and your professor.

FAQ: examples of Chicago style abbreviation examples

Q1. Can you give an example of Chicago-style abbreviation in a footnote?
Yes. Here is a typical note using several abbreviations:

1. John R. Brown, “Rural Health Care in the 1930s,” American Historical Review 118, no. 2 (2013): 215–240.
A later shortened note might read:

5. Brown, “Rural Health Care,” 228.
These are standard examples of Chicago style abbreviation examples for journal articles.

Q2. What are examples of Chicago-style Latin abbreviations I should still know?
You should recognize e.g., i.e., etc., and et al. Chicago still uses et al. in citations and accepts e.g. and i.e. in parentheses and notes. However, in 2024–2025, many instructors ask students to use English phrases like for example and that is in the main text instead.

Q3. Is “U.S.” or “US” the correct Chicago style abbreviation?
Chicago allows both U.S. and US, but many humanities publishers still prefer U.S. with periods. The best practice is to pick one form, use it consistently, and follow your department or journal’s guidelines.

Q4. Are there examples of Chicago style abbreviation examples that differ from APA or MLA?
Yes. For instance, Chicago’s preference for a.m. / p.m. with periods differs from some journal styles that drop the periods. Chicago also relies heavily on abbreviations like ed., trans., and vol. in notes and bibliographies, which look different from APA’s reference list format.

Q5. Should I abbreviate organization names like CDC or NIH in Chicago style?
Yes, but spell them out on first use unless they are overwhelmingly familiar to your audience. For example: According to the Centers for Disease Control and Prevention (CDC), vaccination rates increased in 2024. After that, CDC alone is fine. This pattern mirrors how the organizations abbreviate themselves on their own sites, such as cdc.gov and nih.gov.

If you keep these real-world examples of Chicago style abbreviation examples nearby while you write—especially for notes, bibliographies, and Latin terms—you’ll avoid the most common style errors and keep your professors, editors, and peer reviewers happy.