---
source: https://iinventedlight.com/library/notes/plain-colon-capitalization.md
title: "Capitalize after a colon only when a complete sentence follows"
license: CC-BY-4.0
license_url: https://creativecommons.org/licenses/by/4.0/
source_license: "US government work, public domain; original synthesis in our own words"
license_family: usgov
attribution: "Summary by iinventedlight (AI-assisted). Sources: U.S. Government Publishing Office (govinfo), GPO Style Manual (2016), Chapter 8: Punctuation, US government work, public domain; Digital.gov (GSA), Digital.gov style guide, US government work, public domain."
author: "iinventedlight (synthesis of cited sources); text drafted with AI assistance"
date: 2026-11-09
status: published
checked_on: 2026-11-09
as_of: 2026-11-09
confidence: medium
untested: "Editorial checklist only; not tested with readers. Sources fetched and evidence checked."
category: coverage-gaps
topic_area: "write-edit"
tags: [plain-language, style, punctuation, colon]
client: Librarian
sources:
  - id: S1
    title: "GPO Style Manual (2016), Chapter 8: Punctuation"
    publisher: U.S. Government Publishing Office (govinfo)
    url: https://www.govinfo.gov/content/pkg/GPO-STYLEMANUAL-2016/pdf/GPO-STYLEMANUAL-2016-10.pdf
    accessed: 2026-11-09
    license: "US government work, public domain"
  - id: S2
    title: "Digital.gov style guide"
    publisher: Digital.gov (GSA)
    url: https://digital.gov/style-guide/
    accessed: 2026-11-09
    license: "US government work, public domain"
---
# Capitalize after a colon only when a complete sentence follows

**Answer:** After a colon, capitalize the next word if it starts a complete sentence; lowercase it if a fragment follows.

## GPO detail

- After an introductory independent clause that describes or defines what follows, capitalize the first word of a complete sentence: "His only rule was this: Chickens are not allowed past the front parlor."
- Before a final clause that extends or amplifies the preceding independent clause, lowercase the first word even if a complete sentence follows.
- A colon also introduces a run-in list: "three primary pigment colors: magenta, yellow, and cyan."

## Digital.gov

- After a colon, capitalize the next word if it starts a complete sentence, not a fragment.
- In headlines, the first word after a colon is always uppercase.

## See also

- [plain-serial-comma-for-clarity](https://iinventedlight.com/library/notes/plain-serial-comma-for-clarity/)
- [plain-sentence-case-headlines](https://iinventedlight.com/library/notes/plain-sentence-case-headlines/)

## Claims

- id: C1
  claim: GPO capitalizes a complete sentence after a defining clause and colon.
  source: S1
  evidence: "If a complete sentence follows the colon, capitalize its first word."

- id: C2
  claim: GPO lowercases an amplifying clause after a colon.
  source: S1
  evidence: "Even if a complete sentence follows the colon, lowercase its first word."

- id: C3
  claim: Digital.gov capitalizes after a colon only for a complete sentence.
  source: S2
  evidence: "After a colon, capitalize the next word if it starts a complete sentence"

- id: C4
  claim: Digital.gov headlines capitalize the first word after a colon.
  source: S2
  evidence: "the first word after a colon is always uppercase in headlines"

## Sources

- [S1] GPO Style Manual (2016), Chapter 8: Punctuation. U.S. Government Publishing Office (govinfo). https://www.govinfo.gov/content/pkg/GPO-STYLEMANUAL-2016/pdf/GPO-STYLEMANUAL-2016-10.pdf . License: US government work, public domain. Accessed 2026-11-09.

- [S2] Digital.gov style guide. Digital.gov (GSA). https://digital.gov/style-guide/ . License: US government work, public domain. Accessed 2026-11-09.


License: this note is CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). Summary by iinventedlight (AI-assisted). Sources: US federal government works (GSA, GPO, SEC, CDC), public domain in the United States; third-party quotations inside those works were not used. Text was condensed and changed from the originals.

---

Agents: [/agents.md](/agents.md) | [/.well-known/agent-library.json](/.well-known/agent-library.json).