Result
Not when it is a preposition. "On" is two letters long, and all six major guides keep short prepositions lowercase mid-title. The exception is when "on" works as an adverb that belongs to the verb, as in "Hold On" or "Carry On." Then it is part of the action and gets a capital.
"On" by Style Guide
| Style guide | "On" mid-title | Why |
|---|---|---|
| AP | Lowercase | Prepositions of three or fewer letters stay lowercase |
| APA | Lowercase | Short prepositions (three or fewer letters) stay lowercase |
| Chicago | Lowercase | Prepositions are lowercase at any length |
| MLA | Lowercase | Prepositions are lowercase at any length |
| AMA | Lowercase | Prepositions of three or fewer letters stay lowercase |
| Bluebook | Lowercase | Prepositions of four or fewer letters stay lowercase |
The table covers "on" as a preposition, the way it appears in most titles ("Notes on Writing," "Life on Mars").
Examples in Chicago Style
- Notes on Writing Well
- Life on the Farm
- A Guide on Title Case
- Rain on a Sunday Morning
When "On" Is Capitalized
- As part of a phrasal verb: "Turn It On," "Hold On Tight," "Moving On." Here "on" has no object, so it is an adverb, not a preposition. Chicago states this exception outright. The other guides' lowercase lists name prepositions, not adverbs, so the same reasoning applies.
- First word: "On Writing" and "On the Road" both start with a capital.
- Last word: AP, Chicago, and MLA capitalize the final word ("Something to Lean On").
The quick test: if a noun or pronoun follows "on" and completes its meaning ("on the table," "on it"), keep it lowercase. If "on" finishes the verb's meaning by itself ("log on," "move on"), capitalize it.
Related Words
"Off", "up", and "out" work the same way: lowercase as prepositions, capitalized in phrasal verbs like "Show Off" or "Look Up." The prepositions guide covers the longer ones, such as "upon" and "onto."
Real Titles With "On"
- On the Road (Jack Kerouac): first word, capitalized
- Notes on a Scandal (Zoë Heller): preposition, lowercase
- Carry On (Rainbow Rowell): adverb and last word, capitalized
"On" in Sentence Case
APA reference lists, many news sites, and most UI text use sentence case instead of title case. There, only the first word and proper nouns get capitals, so "on" is lowercase unless it starts the title: "Notes on writing well." Pick one of the two styles for a whole set of headings rather than mixing them.
Quick Answers
Should "on" be capitalized in a title?
Not as a preposition. "On" stays lowercase mid-title in every major guide unless it works as an adverb, as in "Move On."
Is "on" capitalized in APA style?
No, not as a preposition. APA lowercases prepositions of three letters or fewer.
Is "on" capitalized in "Moving On"?
Yes. There "on" is an adverb completing the verb, and it is also the last word, so it is capitalized.
Is "on" capitalized after a colon?
Yes. The first word of a subtitle is always capitalized: "A Field Guide: On Birds and Weather."