Chicago vs MLA Title Case: Tested Differences

Long prepositions create the clearest split

Use the input “a journey through time and beyond.” Tool Packer’s Chicago profile returns “A Journey Through Time and Beyond,” while its MLA profile returns “A Journey through Time and Beyond.” Through is the isolated difference: it exceeds Chicago’s four-letter lowercase-preposition threshold but remains an internal recognized preposition under MLA’s implemented rule.

The shared words show the overlap. Both profiles capitalize the initial A and the major words Journey, Time, and Beyond, and both lowercase the internal coordinating conjunction and. A different long recognized preposition such as between or without creates the same type of mechanical split when it occurs internally.

As, if, yet, and so do not behave alike

Tool Packer’s Chicago profile lowercases internal as but explicitly capitalizes If, Yet, and So. Its MLA profile explicitly capitalizes As and If while treating yet and so as lowercase coordinating conjunctions. Titles built around comparisons or dependent clauses can therefore differ even when every preposition is short.

These are transparent project word-list rules rather than full syntactic analysis. For example, a word may change part of speech with its role in the sentence, and a manual can provide exceptions that no spelling-only lookup captures. Explanations help locate a difference; they do not turn the engine’s classification into a grammatical proof.

• Chicago: as lowercase; If, Yet, and So capitalized.
• MLA: As and If capitalized; yet and so lowercase internally.
• Both profiles lowercase and, but, for, nor, and or internally.

Edition and language scope matter

The Chicago Manual’s official Q&A explains the eighteenth-edition change that capitalizes prepositions longer than four letters. Work governed by an earlier edition or a house style based on one may expect another treatment. MLA’s public guidance describes headline-style capitalization for English titles and directs writers to use the capitalization rules of another language for titles written in that language.

Both Tool Packer profiles capitalize the first word, final word, and a word after a colon, em dash, or line break. They also share acronym restoration, canonical proper terms, request-scoped custom terms, and predictable compound handling. Those shared project features do not replace edition-specific provisions, language knowledge, or manual review of a compound.

• Confirm the required Chicago edition.
• Identify the title’s language before using MLA’s English profile.
• Keep typography and citation formatting separate from casing.

Make the comparison repeatable

Keep the input identical, select each profile in turn, and use explanations to record why a word changed. If a house rule overrides the result, save that decision with the content rather than repeatedly correcting unexplained output. Custom terms can preserve a name or brand’s authoritative spelling for the current request without modifying the global engine.

Tool Packer is independent and is not affiliated with, endorsed by, or certified by the University of Chicago or the Modern Language Association. This page documents a dated, open-source implementation. For publication, academic assessment, contractual copy, or another high-stakes use, the current governing guide and the responsible editor take precedence over the converter.

• Compare one variable at a time.
• Document intentional house-style overrides.
• Review high-stakes titles against current primary guidance.