Style Guide Spelling Decisions
into / in to: Style Guide Spelling Decisions (AP, Chicago, MLA, APA)
How AP, Chicago, MLA, APA, and Merriam-Webster handle the spelling of "into / in to". 'Into' shows direction or transformation; 'in to' is the adverb 'in' followed by the preposition 'to' ('she turned in to the police').
How major style guides rule on "into / in to"
'Into' shows direction or transformation; 'in to' is the adverb 'in' followed by the preposition 'to' ('she turned in to the police').
The disagreement on "into / in to" is an example of compound preposition vs separated adverb-plus-preposition: the category of style-guide differences that most often confuses copy editors and creates inconsistency across long documents. Below is a guide-by-guide breakdown, drawn directly from the published editions cited.
| Style guide | Preferred form |
|---|---|
| AP Stylebook (2024–2025 Edition) | context-dependent |
| Chicago Manual of Style | context-dependent |
| MLA Handbook | context-dependent |
| APA Publication Manual | context-dependent |
| Merriam-Webster Dictionary | context-dependent |
What the divergence actually means
Unlike many compound-modernization decisions where style guides eventually converge, "into / in to" continues to show genuine divergence between major guides. The AP Stylebook treats this as a settled call; Chicago Manual leaves more flexibility; and Merriam-Webster, as a descriptive dictionary, records both forms. Source: Chicago Manual of Style, 17th Edition
The APA Publication Manual aligns with AP and Chicago on "into / in to", though APA generally addresses spelling questions only when they intersect with statistical reporting or technical psychology vocabulary. Where the manual is silent, APA defers to Merriam-Webster as its standard reference. Source: APA Publication Manual, 7th Edition
Merriam-Webster lists "context-dependent", which serves as the lexicographic baseline for U.S. style decisions. Because Merriam-Webster's entries reflect aggregated published usage rather than editorial preference, when a guide says "follow Merriam-Webster", as APA does, that effectively delegates the call to whichever spelling has dominated the published corpus. Source: Merriam-Webster Dictionary
Practical guidance for editors
For working writers, the practical rule is straightforward: in journalism, follow AP; in academic writing in the humanities, follow MLA or Chicago; in social-science publishing, follow APA; in book publishing, follow Chicago. When no house style applies, Merriam-Webster's main entry is the safest default. The differences across these guides on "into / in to" reflect not disagreement about correctness but different audiences and editorial pressures.
Cross-references
For the dictionary entry, frequency data, and pronunciation of into, see the main word page. For other style-guide spelling decisions in this category, browse all style-guide spelling rulings.