Capitalization after a colon depends on the material that follows and the style guide a writer follows. Proper nouns always keep their capitals, but a complete sentence may begin with either a capital or a lowercase letter after a colon. APA style capitalizes that sentence; Chicago style usually lowercases a single sentence and capitalizes a series of two or more sentences.[1][2][3] A word that begins a list, phrase, or other fragment normally stays lowercase unless it requires a capital for another reason.[2][4]
What Are the Rules for Capitalization After a Colon?
The most reliable method is to identify what follows the colon and then apply the required house style. A proper noun such as Mexico, Monday, or Ada Lovelace remains capitalized in every position. A common noun at the start of a list or phrase stays lowercase. A complete sentence requires a style-guide decision: APA uses a capital, while Chicago normally uses lowercase when only one complete sentence follows.[1][5][2]
| Material after the colon | APA-style treatment | Chicago-style treatment | Example |
|---|---|---|---|
| A list or phrase | Lowercase, except proper nouns | Lowercase, except proper nouns | Pack these items: a coat, a map, and gloves. |
| One complete sentence | Capitalize | Usually lowercase | APA: The reason was clear: The gate was locked. Chicago: The reason was clear: the gate was locked. |
| Two or more complete sentences | Capitalize | Capitalize the first word of each sentence | Remember two facts: The office closes at five. The doors lock automatically. |
| A proper noun | Capitalize | Capitalize | She chose one destination: New Zealand. |
| The pronoun I | Capitalize | Capitalize | He knew my answer: I would attend. |
APA calls for a capital when a colon joins two clauses and the words after the colon form a complete sentence.[2][4] Consider this pair:
- APA treatment: The committee reached a decision: The proposal needed another vote.
- Fragment after a colon: The committee requested one change: a later deadline.
The first example has a subject, the proposal, and a complete predicate, needed another vote. The second has only a noun phrase. That grammatical difference determines the APA capitalization.
Chicago makes a different editorial choice. It generally lowercases the first word after a colon within a sentence, even when the following words could stand as a complete sentence.[5] Chicago capitalizes when the colon introduces two or more complete sentences.[5][3]
- One sentence in Chicago style: Mina knew what had happened: the train had left early.
- A series in Chicago style: Mina gave us two updates: The train had left early. The next one would arrive at noon.
These alternatives are conventions, not competing tests of whether the clause is grammatically complete. A document should follow its assigned guide consistently. When no guide is assigned, a writer can select a house style and apply it throughout. Chicago itself describes three workable editorial policies: always capitalize after a colon, always lowercase except where a word independently requires a capital, or capitalize only when a complete sentence follows.[5][5][5]
A colon that introduces a list does not make the first list item a new sentence. The first word therefore stays lowercase unless it is a proper noun.[2]
- Bring three supplies: paper, tape, and scissors.
- We visited three cities: Rome, Accra, and Lima.
- She invited two colleagues: I accepted, but Sam declined.
The first example begins with a common noun. The second begins with a city name. In the third, I retains its normal capital. The reason for each capital is the word itself, not the colon.
How Does the Rule Change Across Style Guides and Contexts?
The main contrast is between styles that capitalize a complete sentence and styles that normally lowercase a single complete sentence. American usage is not perfectly uniform: a complete sentence after a colon is sometimes capitalized, while British usage commonly reserves the capital for a proper noun or acronym.[2] Writers should therefore avoid treating one example as a universal English rule.
Complete sentence in APA style
The forecast contained one warning: Heavy rain would begin after midnight.
The words after the colon form a complete sentence, so APA capitalization applies.[4]
The same sentence in Chicago style
The forecast contained one warning: heavy rain would begin after midnight.
Chicago normally lowercases a single complete sentence after a colon.[5][3]
A Chicago series of sentences
The forecast contained two warnings: Heavy rain would begin after midnight. Strong winds would follow before dawn.
Chicago capitalizes the first words because the colon introduces a series of two complete sentences.[5]
A phrase or fragment
The forecast promised one condition: clear skies.
Clear skies is a noun phrase, not a complete sentence. It begins with a lowercase common adjective.
A list
The kit contains four tools: a compass, a whistle, a flashlight, and a mirror.
The colon introduces a list, so a remains lowercase.[2]
A proper noun
Only one applicant had the required credential: Maria Chen.
The personal name keeps its capitals regardless of the chosen colon style.[1]
A quotation
The witness repeated the warning: “Leave the building now.”
This example presents a complete quoted sentence, whose first word is capitalized. A quotation should not produce a blanket “always capitalize after a colon” rule; the writer must still consider whether the quoted material itself begins with a word that requires a capital. The frozen evidence notes quotations as a context in which a capital can follow a colon, but it does not establish that every quoted fragment must be capitalized.[6]
Bulleted and numbered material requires the same grammatical test. APA capitalizes an item that is an independent clause and lowercases an item that is dependent.[4] For example:
The review produced two findings:
- The original receipt was missing.
- The replacement receipt lacked a date.
Each numbered item is a complete sentence, so each begins with a capital. Compare a phrase list:
The review required two actions:
- finding the original receipt
- checking the date on the replacement
Each item is a phrase and begins lowercase. The label phrase is more accurate here than dependent clause: a phrase has no complete subject-predicate structure, while a dependent clause contains a subject and verb but cannot stand alone.
Which Colon-Capitalization Errors Should You Correct?
Most errors come from applying a complete-sentence rule to a list, mixing APA and Chicago conventions, or overlooking a word that always requires a capital.
Error 1: Capitalizing the first common noun in a list
- Incorrect: Bring these items: Water, snacks, and sunscreen.
- Correct: Bring these items: water, snacks, and sunscreen.
The colon introduces a list, and water is a common noun.[2]
Error 2: Treating Chicago and APA as identical
- APA: The cause was obvious: The battery was empty.
- Chicago: The cause was obvious: the battery was empty.
Both versions can be correct within their respective styles. Calling the lowercase version universally wrong would erase the Chicago convention.[5][2]
Error 3: Lowercasing a proper noun
- Incorrect: The route ended in one city: boston.
- Correct: The route ended in one city: Boston.
Proper nouns retain their capitals after a colon.[1]
Error 4: Capitalizing a phrase as though it were a sentence
- Incorrect: Her goal was simple: Finishing before noon.
- Correct: Her goal was simple: finishing before noon.
Finishing before noon is a phrase, so the common word begins lowercase.[4]
Error 5: Applying Chicago’s series exception to one sentence
- Incorrect explanation: Chicago capitalizes here because a complete sentence follows: The answer was final: No one could appeal.
- Correct Chicago treatment: The answer was final: no one could appeal.
Chicago’s capital-letter exception applies when the colon introduces two or more complete sentences, not merely one.[5][3]
Practice
Apply the named style or grammatical rule. Choose the capitalized or lowercase form in parentheses.
- APA: The delay had one cause: (The/the) road was flooded.
- Chicago: The delay had one cause: (The/the) road was flooded.
- List: Pack the essentials: (Food/food), water, and medicine.
- Proper noun: We chose one city: (Montreal/montreal).
- Chicago series: Keep two rules in mind: (Arrive/arrive) before nine. (Bring/bring) your identification.
- Phrase: The team had one priority: (Finishing/finishing) the safety check.
- Pronoun: She understood my position: (I/i) would not sign.
- APA: The result surprised us: (Every/every) sample passed the test.
Answer key
- The — APA capitalizes a complete sentence after a colon.[4]
- the — Chicago normally lowercases one complete sentence.[5]
- food — a common noun begins the list.[2]
- Montreal — a proper noun keeps its capital.[1]
- Arrive; Bring — Chicago capitalizes a series of two complete sentences.[5]
- finishing — the words form a phrase, not a sentence.[4]
- I — the pronoun is always capitalized.[6]
- Every — APA capitalizes the complete sentence that follows.[2]