Capitalization Rules in English: The Complete Guide

Getting the Fundamentals Straight

Capitalization is the act of starting a word with an uppercase letter, and it carries more meaning than many writers realize. English sits in the middle of the spectrum: it capitalizes less than German (which capitalizes every noun) and more than French (which barely bothers outside of names and sentence starts). Once you know the handful of underlying patterns, writing polished, consistent text gets much easier.

Almost every rule in English capitalization is really one rule in disguise: treat proper nouns — the specific names of people, places, and things — differently from common nouns, which label categories. Capitalize the first; leave the second lowercase. Take a look at dictionary.wiki for more background on how words are classified in the first place.

The First Word of a Sentence

Every sentence starts with a capital letter. This holds whether the sentence is quoted, begins with a number, or follows a colon that introduces a full clause:

• Our flight was delayed by three hours.
• Maria turned to me and said, "Don't wait up."

Sentences That Follow a Colon

Style guides disagree here. Most recommend a capital letter when the colon introduces what could stand alone as its own sentence. Our deeper colon rules piece lays out the options in more detail.

Brands That Insist on a Lowercase Letter

A handful of brand names (iPhone, eBay, iPad) deliberately start with a lowercase letter. When such a name opens a sentence, many editors capitalize anyway — "IPhone sales climbed." Others simply rewrite the sentence so the brand lands somewhere in the middle instead.

Proper Nouns and Common Nouns

This is the big one — the distinction that drives most other rules in the language:

Groups That Are Always Capitalized

• Individual names: Marie Curie, Toni Morrison, Nelson Mandela.
• Languages and nationalities: Italian, Korean, Nigerian, Finnish.
• Religions and their adherents: Islam (Muslims), Sikhism (Sikhs), Buddhism (Buddhists).
• Historical periods and events: the Cold War, the Enlightenment, the French Revolution.
• Named geography: Mount Kilimanjaro, the Thames, Hyde Park.
• Brands and products: Adidas, Honda, Samsung.

Titles Attached to People

A job title or honorific gets a capital letter only when it sits immediately before a person's name. Used on its own as a description, it stays lowercase:

• Senator Nguyen spoke first. / The senator spoke first.
• Coach Rivera called the play. / The coach called the play.
• Emperor Meiji reformed the government. / The emperor reformed the government.
• Dr. Okafor runs the clinic. / The doctor runs the clinic.

Family terms follow the same logic. Capitalize them when they stand in for a name, leave them lowercase after a possessive:

• Happy birthday, Dad! (used as a name)
• I called my dad this morning. (possessive pushes it back to lowercase)
• Grandma Odette taught me to sew. / My grandma taught me to sew.

Naming Books, Films, and Other Works

Titles of creative works have two main capitalization systems, and you pick one based on the style guide you're following:

Title Case

Capitalize every significant word. Leave articles (a, an, the), short prepositions (of, in, at), and coordinating conjunctions (and, but, or) lowercase — unless they open or close the title:

• Pride and Prejudice
• One Hundred Years of Solitude
• The Grapes of Wrath
• A Room with a View

Sentence Case

Treat the title like a regular sentence: capitalize only the first word plus any proper nouns. This is standard in APA references and many scientific journals:

• Pride and prejudice (APA references list)
• One hundred years of solitude

Which Style Guide Prefers Which?

Cities, Mountains, and Other Places

Capitalize the specific name of a place. Leave the generic category word lowercase when it stands alone:

• the Indian Ocean / the ocean
• the Alps / the mountains
• Loch Ness / the loch
• the Gobi Desert / the desert

The generic word flips to uppercase when it is genuinely part of the official name, and back down when you're speaking loosely:

• We paddled down the Danube River for a week. (official name)
• We swam in the river below the bridge. (generic reference)

Calendar Words: Days, Months, Holidays, Seasons

Capitalize

• Weekdays: Monday, Tuesday, Sunday.
• Months: April, August, November.
• Holidays: Eid al-Fitr, Easter, Passover, Lunar New Year.

Leave Lowercase

• Seasons: spring, summer, autumn (or fall), winter.

The exception: a season that is part of a proper name does get a capital — "the Spring 2025 cohort," "the Winter Olympics."

Companies, Schools, and Institutions

Every substantive word in the official name of a company, school, agency, or organization is capitalized:

• the World Health Organization
• Stanford University
• the European Central Bank
• Netflix, Spotify, Toyota

Drop back to lowercase when you are talking about an unnamed, generic example:

• She enrolled at a liberal arts college. (no specific school)
• He joined a nonprofit after graduation. (unnamed)

What to Do After a Colon

This is a long-running editorial debate. The major guides boil down roughly as follows:

• Chicago: capitalize only when the colon introduces two or more complete sentences, or a formal statement.
• AP: capitalize when what follows is a complete sentence.
• APA: capitalize when what follows is a complete sentence.

The fuller treatment lives in our colon rules guide, with examples and edge cases.

Compass Points vs Named Regions

This one trips up almost everyone at some point:

• Capitalize a direction word when it names a recognized region: the South, the Midwest, the Pacific Northwest, Southeast Asia.
• Keep it lowercase when it simply tells you which way something faces or moves: drive north for ten minutes; the wind blew in from the east.

She's been reporting from the South for two decades. (region)

The hurricane is tracking south overnight. (direction)

Edge Cases Worth Knowing

Internet, Web, and Related Terms

Attitudes have shifted. Almost every major guide now treats internet and web as ordinary lowercase nouns. Older references — particularly editions printed before the mid-2010s — still capitalize them.

The Pronoun "I"

Always uppercase, anywhere it appears. No other personal pronoun in English gets this treatment.

After an Interjected Question Mark or Exclamation Mark

If a question or exclamation is inserted mid-sentence (between dashes or inside parentheses), the next word does not take a capital:

The message — have you read it yet? — made everyone uneasy.

Acronyms and Abbreviations

Standard acronyms are written in all caps: WHO, EU, NASA, FIFA. A handful have become so entrenched that they have lost their capitals altogether and are treated as ordinary words — laser, radar, and scuba are the usual examples.

Mistakes People Make Most Often

Capitalizing Seasons

Incorrect: I always travel in Summer.

Correct: I always travel in summer.

Capitalizing a Compass Direction

Incorrect: Head West at the roundabout.

Correct: Head west at the roundabout.

Uppercasing Ordinary Nouns for Emphasis

Incorrect: The Firm announced a new Product this Quarter.

Correct: The firm announced a new product this quarter.

Forgetting the Capital After a Period

The first word of any new sentence takes a capital, even in a casual text or a quick note to a friend.

Mixing Styles in One Document

Pick either title case or sentence case for your headings and stick with it from start to finish. Switching mid-document looks careless, even if nobody can articulate why.

The Short Version

• Capitalize the first word of every sentence, without exception.
• Capitalize proper nouns; leave common nouns alone.
• Capitalize a title only when it precedes a name.
• Capitalize weekdays, months, and holidays; leave seasons lowercase.
• Capitalize named regions (the South); lowercase plain compass directions (drive south).
• Pick a titling style (title case or sentence case) and apply it consistently.
• The pronoun "I" is always capitalized.
• When in doubt, consistency beats cleverness.

For more in this corner of style and mechanics, see our pieces on abbreviations and acronyms, numbers in writing, and punctuation marks.