Result
It depends on the style guide. "Into" is a four-letter preposition. AP, APA, and AMA capitalize prepositions of four or more letters, so they write "Into." Chicago and MLA lowercase all prepositions, and Bluebook lowercases those of four letters or fewer, so those three keep "into" lowercase mid-title.
"Into" by Style Guide
| Style guide | "Into" mid-title | Why |
|---|---|---|
| AP | Capitalize | Prepositions of four or more letters are capitalized |
| APA | Capitalize | Words of four or more letters are capitalized |
| Chicago | Lowercase | Prepositions are lowercase at any length |
| MLA | Lowercase | Prepositions are lowercase at any length |
| AMA | Capitalize | Only prepositions of three or fewer letters stay lowercase |
| Bluebook | Lowercase | Prepositions of four or fewer letters stay lowercase |
The Same Headline in Four Styles
| Style | "a deep dive into title case" |
|---|---|
| AP | A Deep Dive Into Title Case |
| APA | A Deep Dive Into Title Case |
| Chicago | A Deep Dive into Title Case |
| MLA | A Deep Dive into Title Case |
| Style | "turning readers into customers" |
|---|---|
| AP | Turning Readers Into Customers |
| APA | Turning Readers Into Customers |
| Chicago | Turning Readers into Customers |
| MLA | Turning Readers into Customers |
"Into" Versus "In To"
Sometimes "in" and "to" sit next to each other without forming "into": "Log In to Your Account." There, "In" is an adverb completing "log in," so it is capitalized, and "to" is a separate preposition that stays lowercase. Use "into" only for movement or transformation, as in "Walk Into the Room" or "Turn Leads Into Sales" (both AP style).
Related Words
"From", "with", and "over" are also four letters and split the guides the same way. "In" and "to" on their own are lowercase everywhere.
Real Titles With "Into"
- Into the Wild (Jon Krakauer): first word
- Into Thin Air (Jon Krakauer): first word
"Into" 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 "into" is lowercase unless it starts the title: "Turning readers into customers." Pick one of the two styles for a whole set of headings rather than mixing them.
Quick Answers
Should "into" be capitalized in a title?
In AP, APA, and AMA, yes. In Chicago, MLA, and Bluebook, no, unless it is the first or last word.
Is "into" capitalized in APA?
Yes. "Into" has four letters, and APA capitalizes words of four letters or more.
Is "into" capitalized in Chicago style?
No. Chicago lowercases prepositions at any length.