Title Case Rules Explained
Title case rules vary by style guide. The three major styles differ mainly in how they treat prepositions and conjunctions:
Chicago Style (default)
Capitalize all words except articles (a, an, the), coordinating conjunctions (and, but, or, nor, for, so, yet), and prepositions of four letters or fewer (in, on, at, to, up, as, by, of, off, via). Always capitalize the first and last word regardless of type.
Example: The Cat in the Hat Comes Back
AP Style
AP (Associated Press) capitalizes all words of four letters or more. Short prepositions, articles, and conjunctions under 4 letters are lowercase. Similar to Chicago but the threshold for prepositions is strictly length-based.
Example: War and Peace in the Modern Era
APA Style
APA (American Psychological Association) capitalizes all major words including longer prepositions (e.g., Between, Among, Through) and is commonly used in academic writing for journal article titles.
When to Use Which Case Format
- UPPER CASE — headings, emphasis, acronyms, legal headers
- lower case — poetry formatting, informal style, email subjects in some styles
- Title Case — book titles, movie titles, article headings, UI navigation labels
- Sentence case — most general-purpose writing, email subjects, blog post bodies
- camelCase — JavaScript variables, JSON keys, iOS Swift method names
- PascalCase — class names, React component names, TypeScript types
- snake_case — Python variables, database column names, file names on Linux
- kebab-case — CSS class names, URL slugs, HTML data attributes, CLI flags
- CONSTANT_CASE — environment variables, configuration constants, Enum values
- dot.case — config file keys (logging.level), Java package names