Writing Center
SMC Campus Center
621 W. Lombard St. Room 307
www.umaryland.edu/writing
410-706-7725
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Unnecessary Comma: Bill, and Tom went to the store.
Note: “Bill” and “Tom” are the subjects of the sentence. Since there are only two subjects, there is no need to
separate them with a comma.
Unnecessary Comma: Walking the dog, and buying groceries are my least favorite activities.
Note: “Walking the dog” and “buying groceries” are gerund phrases acting as the subjects of the sentence.
Since there are only two subjects, there is no need to separate them with a comma.
Necessary Comma: John, Paul, and George are my favorite Beatles
Note: “John,” “Paul,” and “George” are the subjects of the sentence. Since there are three subjects, commas
are necessary.
Unnecessary Commas with Compound Predicates
The predicate is the part of the sentence that contains the verb and says something about the subject.
Unless you have a list of three or more predicates, there’s no need to separate predicates with
commas.
People often make this error by thinking they are combining two independent clauses. Remember that,
when joining two independent clauses, each independent clause will have a separate subject and
predicate.
Unnecessary Comma: She went to the post oce, and mailed a letter.
Note: “Went to the post oce” and “mailed a letter” are both predicates connected to the subject “she.”
Since there are only two predicates, there is no need to separate them with a comma.
Unnecessary Comma: He runs on lakes and trails, and swims in rivers and lakes.
Note: “Runs on lakes and trails” and “swims in rivers and lakes” are both predicates connected to the subject
“he.” Since there are only two predicates, there is no need to separate them with a comma.
Necessary Comma: They paint houses, repair fences, and dig ditches.
Note: “Paint houses,” “repair fences,” and “dig ditches” are all predicates attached to the subject “they.” Since
there are three predicates, the commas are necessary.
Omitted Commas with Direct Address
Omitting commas when addressing someone directly can lead to unintentionally humorous sentences. In
fact, remembering these humorous mistakes can help you avoid this problem.
Without Commas (Cannibalism): Let’s eat Grandma!
With Commas (Respect for the Elderly): Let’s eat, Grandma!
References
Fogarty, M. (2008). Grammar girl’s quick and dirty tips for better writing. New York, NY: St. Martin’s Grin.
Straus, Jane. (2008). The blue book of grammar and punctuation: An easy-to-use guide with clear rules, real-world examples,
and reproducible quizzes. San Francisco, CA: Jossey-Bass.
Thurman, Susan. (2003). The only grammar book you’ll ever need: A one-stop source for every writing assignment. Avon, MA:
Adams Media.
Truss, L. (2003). Eats, shoots & leaves: The zero tolerance approach to punctuation. New York, NY: Gotham Books.