Punctuation Junction: Commas and Semicolons

by Chelsea Lee

Punctuation Junction: A series about what happens when punctuation marks collide.

Commas and semicolons separate parts of sentences from one another. Although each mark has plenty of uses on its own, there are several more complex scenarios in which the marks are used together. Learn how to avoid grammar gridlock by following the punctuation guidelines shown below.

1. Separate independent clauses joined by a conjunction (and, or, but, etc.) with commas; separate independent clauses not joined by a conjunction with semicolons. Use commas within clauses as needed. 

• Correct: Some errors are more major than others; for instance, calling a tiger a mouse is a larger error than calling a tiger a lion, and adults may be less forgiving of large errors than small ones.
• Incorrect: Some errors are more major than others, for instance, calling a tiger a mouse is a larger error than calling a tiger a lion, and adults may be less forgiving of large errors than small ones.

2. Separate items in a list with commas; however, if any item already contains commas, separate the items with semicolons. 

• Correct: Even in families where books are absent, leaflets and magazines offer text-based information about consumables and services; e-mails and text messages can give information on the whereabouts, plans, and activities of friends; and computers may be used to find out about films or prices of consumables and holidays.
• Incorrect: Even in families where books are absent, leaflets and magazines offer text-based information about consumables and services, e-mails and text messages can give information on the whereabouts, plans, and activities of friends, and computers may be used to find out about films or prices of consumables and holidays.

3. Separate multiple citations within one set of parentheses with semicolons; separate author(s) and date within citations with commas. 

• Correct: Recent research in developmental psychology has explored this issue, often using the term selective trust to describe the ability to distinguish who should be trusted from who should not (e.g., Bergstrom, Moehlmann, & Boyer, 2006; Clément, 2010; Harris & Corriveau, 2011; Harris & Koenig, 2006; Heyman, 2008; Heyman & Legare, in press; Koenig & Harris, 2005).
• Incorrect: Recent research in developmental psychology has explored this issue, often using the term selective trust to describe the ability to distinguish who should be trusted from who should not (e.g., Bergstrom Moehlmann & Boyer 2006, Clément 2010, Harris & Corriveau 2011, Harris & Koenig 2006, Heyman 2008, Heyman & Legare in press, Koenig & Harris 2005).

For more on how commas and semicolons are used independently, see Publication Manual §4.03 and §4.04. Keep an eye out for more Punctuation Junction posts coming soon!

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Examples 1 and 3 adapted from “Knowing When to Doubt: Developing a Critical Stance When Learning From Others,” by C. M. Mills, 2013, Developmental Psychology, pp. 404, 406. Copyright 2013 by the American Psychological Association.

Example 2 adapted from “Reading to Learn: Prereaders’ and Early Readers’ Trust in Text as a Source of Knowledge,” by E. J. Robinson, S. Einav, & A. Fox, 2013, Developmental Psychology, p. 512. Copyright 2013 by the American Psychological Association.