Rules for writers, Tenth edition - Diana Hacker, Nancy Sommers 2021

Know your options when the first word after a colon begins an independent clause
Capitalization
Mechanics

When a group of words following a colon can stand on its own as a complete sentence, MLA recommends using lowercase for the first word except in certain situations (such as if the sentence following the colon is a question). APA calls for capitalizing it.

MLA STYLE

Clinical trials revealed a problem: a high percentage of participants reported severe headaches.

APA STYLE

Clinical trials revealed a problem: A high percentage of participants reported severe headaches.

Always use lowercase for a list or an appositive that follows a colon (see 36a).

Students were divided into two groups: residents and commuters.

EXERCISE 46-1

Edit the following sentences to correct errors in capitalization. If a sentence is correct, write “correct” after it. Answers appear in the back of the book.

a. Assistant dean Shirin Ahmadi recommended offering more world language courses.

b. We went to the Mark Taper Forum to see a production of Angels in America.

c. Kalindi has an ambitious semester, studying differential calculus, classical hebrew, brochure design, and greek literature.

d. Lydia’s Aunt and Uncle make modular houses as beautiful as modernist works of art.

e. The labs in Ohio began their research in the Spring, and we expect clinical trials to start at our Cleveland lab next Summer.