How to Capitalize Hyphenated Words in a Title

Take the title a follow-up study of self-esteem in pre-school children. Put it into title case and three hyphens need three decisions. Is it Follow-Up or Follow-up? Self-Esteem or Self-esteem? Pre-School or Pre-school? The guides have answers, and they do not all agree, but the logic is simpler than it looks.

The general rule

Treat each half of a hyphenated word the way you would treat it if it stood alone. If the second half is a noun, verb, adjective or adverb, it is a major word and gets a capital. If it is an article, a short preposition or a coordinating conjunction, it is a minor word and stays lowercase.

• Self-Esteem: esteem is a noun, so it is capitalized.
• Long-Term Outcomes: term is a noun.
• Well-Being: being is a noun.
• Mother-in-Law: in is a preposition and stays small; Law is a noun and does not.
• Face-to-Face Interviews: to stays small.

This is the rule in APA 7, MLA 9 and, in practice, AP. The title case converter applies it for all of those styles.

"Follow-up" and other particles

The second half of follow-up is up, a two-letter preposition. By the general rule it stays lowercase: A Follow-up Study. Many journals write Follow-Up anyway, treating the whole compound as one noun. APA 7's own examples use Follow-up, so if you are writing for an APA journal, keep the u small. If you are writing for a journal that uses Follow-Up in its own titles, match the journal. The same logic applies to Check-in, Sign-up, Start-up and Log-in when they are used as nouns.

Prefixes: the Chicago exception

Chicago adds a rule the others do not state. When the first element of a hyphenated word is a prefix or combining form that cannot stand on its own (anti-, pre-, post-, co-, re-, non-, e-), the second element is lowercase, unless it is a proper noun or adjective:

• Chicago: Pre-school Education, Anti-inflammatory Drugs, Re-entry Programs
• Chicago: Post-Soviet Politics (proper adjective, so capital)

APA does not make this exception. By the length rule, School has six letters and is a noun, so APA writes Pre-School. MLA follows the general rule as well, so Pre-School there too. This is the one hyphen case where the guides visibly disagree. The converter on this site follows the general rule and writes Pre-School in every style, so if your guide is Chicago, check prefix compounds by hand and lowercase the second element.

Numbers

Spelled-out numbers capitalize both parts in every guide: Twenty-One Days, Thirty-Five Years of Research, Ninety-Nine Problems. Fractions do too: Two-Thirds of the Sample.

Hyphens that join a word to a name

When one half is a proper noun, it keeps its capital wherever it falls: Anglo-American Relations, Post-Brexit Trade, the Mid-Atlantic States. The other half follows the normal rule for its part of speech.

Letters and single characters

E-mail and E-Commerce, X-Ray and X-ray, T-Shirt and T-shirt: these vary by guide and by house style more than any other case. APA writes E-Mail and X-Ray in titles by its general rule. Chicago, treating e- as a prefix, writes E-mail. If the word appears in your target journal's own article titles, copy what they do.

Dashes are not hyphens

An en dash joining two equal terms (Mother–Infant Attachment, Cost–Benefit Analysis) and an em dash introducing a subtitle (Lost Cities—A Field Guide) both behave like the start of a new word group: the word after the dash is capitalized exactly as it would be after a colon. In practice that means it is almost always capitalized.

The quick version

1. Capitalize the second half if it is a noun, verb, adjective or adverb: Self-Esteem, Long-Term.
2. Keep it lowercase if it is an article, a short preposition or a conjunction: Mother-in-Law, Follow-up.
3. In Chicago, keep it lowercase after a prefix that cannot stand alone: Pre-school, Anti-inflammatory. The converter does not apply this exception, so it is the one hyphen to check by hand.
4. Both halves of a spelled-out number: Twenty-One.
5. Proper nouns keep their capitals wherever they fall.

Then paste the title into the capitalization tool with your style selected and compare. If the two agree, you are done. If they differ on one hyphen, it is almost always a prefix case, and the house style wins.