Major Rule Changes in The Chicago Manual of Style, Fifteenth Edition

This list has been prepared for those who use The Chicago Manual of Style regularly, know its rules for capitalization, punctuation, and so forth, and want to know which rules have been changed for the fifteenth edition. The list presents a selection of the most significant rule changes, in order of appearance.

Other major changes—reorganizations or additions of material, including new coverage of technological shifts and their effect on writing, editing, and publishing—are not covered here; they are described in “What’s New in the Fifteenth Edition.”

Chapter numbering has changed to reflect an added chapter on grammar and usage (chapter 5) and streamlined coverage of design and production (appendix A). Some chapter titles have been modified slightly. (See also the full table of contents.)

  • Preface
  • Acknowledgments
  • 1 The Parts of a Published Work
  • 2 Manuscript Preparation and Manuscript Editing
  • 3 Proofs
  • 4 Rights and Permissions
  • 5 Grammar and Usage
  • 6 Punctuation
  • 7 Spelling, Distinctive Treatment of Words, and Compounds
  • 8 Names and Terms
  • 9 Numbers
  • 10 Foreign Languages
  • 11 Quotations and Dialogue
  • 12 Illustrations and Captions
  • 13 Tables
  • 14 Mathematics in Type
  • 15 Abbreviations
  • 16 Documentation I: Basic Patterns
  • 17 Documentation II: Specific Content
  • 18 Indexes
  • Appendix A Design and Production—Basic Procedures and Key Terms
  • Appendix B The Publishing Process for Books and Journals
  • Bibliography
  • Index

Punctuation and font. Preference is now given to setting commas, semicolons, periods, and colons in the font of the surrounding text. Question marks and exclamation points are (as before) italic only if they belong to the word they follow. The traditional system is fully acceptable, however. 6.3–7.

Dates. The month-day-year form (e.g., July 1, 2003) is now preferred; the day-month-year form (e.g., 1 July 2003) is a fully acceptable alternative, especially in documentation that includes numerous precise dates. 6.46.

Embedded questions. A short direct question included within a sentence need not begin with a capital letter, but it is still preceded by a comma. 6.55.

2-em and 3-em dashes. A 2-em dash rather than a 3-em dash is now used to represent a complete missing word or name in running text. The 3-em dash is still used in bibliographies to represent the author’s name repeated from the immediately preceding entry. 6.95–96.

Plurals and possessives. For acceptable alternatives for plurals and possessives, see 7.19–22, 7.27.

Possessive versus attributive forms. A strong preference is expressed for retaining the apostrophe in plural forms (e.g., employees’ cafeteria, consumers’ group). 7.27.

Punctuation with a single closing quotation mark. A comma or a period follows a single closing quotation mark in linguistic and botanical usage. (This rule no longer applies to special terms used in philosophy, since single quotation marks are now discouraged in this context.) 7.52, 8.138.

Plurals of letters. With lowercase letters used as letters, an apostrophe is used in the plural form (e.g., x’s and y’s). 7.65.

Letters representing shapes. The rule about using sans serif type for letters representing shapes has been abandoned (e.g., an L-shaped room). 7.67.

Hyphenation. The rule about omitting the hyphen in modified hyphenated compounds has been abandoned (e.g., a very well-read student, where very is taken to modify well-read, not just well). 7.90.

Titles of nobility. Titles of dukes, earls, and such are dealt with in a more British way, according to context and following The Times Guide to English Style and Usage (e.g., the Duke of Kent). 8.34.

Plurals of proper nouns that include a generic term. As in the twelfth and thirteenth editions of the Manual, the generic term in a proper noun is lowercased if used in the plural (e.g., Fifty-fifth and Fifty-seventh streets, the Thames and Mersey rivers, the American and French revolutions). 8.57, 8.60, 8.121.

Books of the Bible. The word book is lowercased in references to the Bible (e.g., the book of Job). Also, the full name of biblical books may be used with chapter and verse (e.g., Genesis 1:21) unless numerous references of this kind occur. 8.113, 9.30, 15.48.

Capitalizing hyphenated terms in titles of works. A simple rule is offered in addition to the traditional, more complex rules for capitalizing hyphenated terms in titles of works. Also, one no longer needs to capitalize the last element of a hyphenated term just because the compound is the last word in a title (e.g., Avoiding a Run-in). 8.167–70.

Ordinals. Chicago’s former preference for the shorter forms of ordinals has been dropped; 2nd and 3rd are now generally recommended over 2d and 3d except in legal citation. 9.8.

Time of day. Lowercase p.m. with periods is now preferred to small-cap pm, though the small-cap form is fully acceptable. When small caps are used, there is no need for periods. 9.42, 15.44.

Dates in book and chapter titles. The full form of dates is recommended for book titles (e.g., The Great War, 1914–1918), but the shortened form is fine for chapter titles, captions, and such (e.g., 1914–18). 9.68.

Ellipsis points. Three methods are now offered: three-dot, three-plus-four-dot, and “rigorous” (the last being a refinement of the first two for use where strict textual fidelity is required). All material on ellipses has been gathered into one section. 11.51–66.

Figure captions. Sentence-style capitalization is recommended for all captions, whether full or incomplete sentences. The former distinction between legend and caption has been modified, and a definition of label has been added. 12.8, 12.32.

Table titles and column heads. Sentence-style rather than headline-style capitalization is recommended for table titles and column heads, especially where tables and figures within one work deal with the same or similar data. All sample tables show this style. 13.16, 13.19.

Abbreviations and periods. In general, periods are omitted from abbreviations in full caps or small caps but retained in lowercase abbreviations (except in scientific style). U.S. retains the periods. 15.4–5, 15.34.

Abbreviations for states and provinces. The two-letter abbreviations used in postal codes for states and provinces are now recommended, with the traditional forms an option. 15.29–30.

Place-names with “St.” or “Saint.” Chicago no longer requires that St. be spelled out; either St. Louis or Saint Louis is acceptable. Names beginning with St. are alphabetized with other words beginning with st, not as if they were spelled Saint. 15.32, 18.91.

Full caps versus small caps. Certain abbreviations traditionally set in small caps are now in full caps (AD, BCE, and the like), with small caps an option. 15.41.

Permissible changes in cited titles. It is no longer recommended that numerals be treated the same in cited titles as in running text (e.g., 12th Century need not be edited to Twelfth Century in a bibliography). 17.52.

Citing notes. In both documentation and indexes, when both page and note numbers appear, the period is omitted after n, and no space appears on either side (e.g., 192n23). The former style remains an option (192, n. 23). 17.139–40, 18.111–13.

Seasons. Names of seasons remain lowercase in text, but when a season stands in place of a month in documentation, it is capitalized. 17.164.

Editions of the classics. The rule about omitting publication details for the Loeb classics and similarly well-known editions has been dropped. 17.259.

Legal citations. Examples are now given primarily in Bluebook and ALWD style, with University of Chicago style an option. 17.275–89.

“Mac” and “Mc.” Names beginning with Mac or Mc are alphabetized letter-by-letter as they appear, not mixed together as if they all were spelled Mac. 18.71.

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