Prefix-Based Hyphenated Compounds in Title Case
Chicago 18 changed how later elements in prefix-based hyphenated compounds are capitalized: each component now follows the general title-case rule. Safe automatic treatment still requires recognizing that the hyphen truly joins a reviewed prefix compound.
In Chicago 18, a retained hyphen in a prefix-based compound no longer automatically forces a lowercase second element. Reviewed examples support forms such as “Co-Founder” and the 18th-edition pattern “Anti-Intellectual.”
Key details
Important caveats
Automation boundary
Reviewed prefix patterns can be handled consistently, but arbitrary hyphenated compounds should not be assumed to be prefix compounds.
Further guidance
Chicago 18 Rule
Chicago’s 18th-edition change summary says later elements in a hyphenated term beginning with a prefix are capitalized according to the general title-capitalization rule.
Practical Application
Under Chicago 18, a retained hyphen in a prefix-based compound no longer automatically forces the second element lowercase. Apply the general title-case rule to each component once you have established that the form is genuinely a reviewed prefix compound.
Reader Check
Do not capitalize mechanically from the presence of a hyphen. First identify the compound type and the governing style; other style systems may use different rules.
Reviewed Prefixes
Chicago’s Q&A supplies reviewed prefix-compound examples including co-founder, anti-intellectual, pro-life/pro-choice, sub-Saharan, and pre-1950 forms.
Worked Example
Chicago 18 examples support forms such as “Co-Founder” and “Anti-Intellectual.” A title-case engine should classify the compound before changing either side of the hyphen.
Sources and evidence
Sources are shown with the role they play in this guide. Historical or style-sensitive claims are kept within the evidence boundary described above.
- What's New in the 18th Edition (opens in a new tab)The Chicago Manual of Style / University of Chicago Press · Chicago 18 title-case terminology and five-letter-preposition change
- Chicago guidance on co-founder and hyphenated title capitalization (opens in a new tab)The Chicago Manual of Style · Reviewed co- prefix title-case example
- Chicago guidance on prefix compounds and hyphenation (opens in a new tab)The Chicago Manual of Style · Reviewed prefix-compound forms and hyphenation examples
- Headlines and Titles of Works — Chicago Q&A (opens in a new tab)The Chicago Manual of Style / University of Chicago Press · Chicago title-case rules and current-edition updates