Punctuation and capitalization

When it comes to the question of whether to capitalize the first word after a semicolon or colon, the answer is likely “it depends”.

Often, the decision requires identifying the independent and dependent clauses in the sentence. As a reminder, independent clauses, also known as restrictive clauses, contain a subject and a verb and can act as a sentence without additional information; e.g., the sun is shining. Independent clauses present the essential information in a sentence. Dependent clauses, also known as nonrestrictive clauses, may also contain a subject and a verb, but they are incomplete sentences that need an independent clause to make sense, e.g., which is a pleasant surprise. A dependent clause provides non-essential information, and if removed, the remaining sentence would still make sense. Together, independent and dependent clauses create descriptive sentences: The sun is shining, which is a pleasant surprise.

Please see below for an explanation of when to capitalize the word after a semicolon or colon:

Semicolon

• Do not capitalize the first word in a list after a semicolon unless the word is a proper noun, e.g., During Julie's vacation, she visited many Canadian cities, including St. John's, which is one of Canada's oldest cities; Ottawa, which is Canada's capital city; and Toronto, which is Canada's largest city.
• When using a semicolon to join two independent clauses, do not capitalize the first word of the second independent clause unless the word is a proper noun, e.g., The sky is blue; the birds are singing.
• Capitalize an author's name after a semicolon in a multi-author citation, e.g., (Brown & Lee, 2010; Johnson & Smith, 2009).

Colon

• When using a colon to join two clauses, capitalize the first word of the clause after the colon if it is a complete sentence (American Psychological Association [APA], 2020, p. 156), e.g., Flooding caused road closures on January 28, 2016: Highway 1A and Cowichan Bay Road were both affected by washouts (Harnett, 2016).
• Do not capitalize the first word of a dependent clause after a colon, e.g., I have three tasks to complete before my document is finished: check my references, proofread for typos, and read the document out loud to ensure the text makes sense.
• When deciding whether to capitalize the first word of a bulleted or numbered item, consider whether the item is an independent or a dependent clause. If the item is an independent clause, capitalize the first word (APA, 2020, p. 190). If the item is a dependent clause, do not capitalize the first word (APA, 2020, p. 190).
• Capitalize the first word of a subtitle in a reference (APA, 2020, p. 167), e.g., This is the title: This is the subtitle.

References

American Psychological Association. (2020). Publication manual of the American Psychological Association (7th ed.). https://doi.org/10.1037/0000165-000

Harnett, C. (2016, January 28). Crofton-area road closed by washout; Trans-Canada traffic flowing. Times Colonist. https://www.timescolonist.com/news/local/crofton-area-road-closed-by-washout-trans-canada-traffic-flowing-1.2160792