Comma Usage

Separate two main clauses with a comma only when they are joined by a coordinating conjunction.

A comma cannot separate main clauses unless they are linked by a coordinating conjunction.

Comma splice: Walters State offers many degree programs, many of the programs are transfer degrees.

Revised: Walters State offers many degree programs, and many of the programs are transfer degrees.

Note: If the two ideas expressed in the main clauses are very closely related, a semicolon can be used to separate them. Also a period can be used to create two sentences.

Follow transitional expressions, including conjunctive adverbs, with commas.

Words that are not conjunctions can describe how one main clause relates to another.

• Conjunctive adverbs such as consequently, finally, hence, however, indeed, therefore, or thus.
• Other transitional expressions such as even so, for example, in fact, of course, to the right, and to this end.

Example: Most Americans refuse to give up unhealthful habits; consequently, our medical costs are higher than those of many other countries.

Use a comma before and, but, or another coordinating conjunction linking main clauses.

The coordinating conjunctions are and, but, or, nor, for, so, and yet. When a coordinating conjunction is used to link words or phrases, no comma is needed. However, when joining two main clauses with a conjunction, do use a comma. The main clauses should contain both a subject and predicate and make a complete statement.

Incorrect: Caffeine can keep coffee drinkers awake, and elevate their mood.

Correct: Caffeine can keep coffee drinkers awake, and it may elevate their mood.

Note: An exception to this rule is when the main clauses in a sentence are very long or grammatically complicated, or when they contain internal punctuation. A semicolon before the coordinating conjunction will clarify the division between clauses.

Use commas to set off most introductory elements.

An introductory element modifies a word or words in the main clause that follows. These elements are usually set off from the rest of the sentence with a comma.

Incorrect: At Walters State Community College a number of tutoring services are available to students.

Correct: At Walters State Community College, a number of tutoring services are available to students.

Note: The comma may be omitted after short introductory elements if its omission does not create confusion. If in doubt, however, the comma is always correct.

Use a comma or commas to set off nonessential elements.

Place commas around a part of a sentence that is not necessary or essential to the meaning of the sentence.

Incorrect: Morristown which is Davy Crockett's hometown is located in Hamblen County.

Correct: Morristown, which is Davy Crockett's hometown, is located in Hamblen County.

Note: A part of a sentence that is necessary or essential need not be set off by commas.

Essential: Walters State Community College rewards students who work hard.

The bolded phrase is an essential part of the sentence's meaning because without it the meaning of students would be too general.

Use a comma or commas to set off absolute phrases.

An absolute phrase modifies a whole main clause instead of a word in the clause, and the phrase usually contains at least one participle and a subject. Absolute phrases can occur anywhere in a sentence and are always set off by commas.

Correct: Anderson State Community College, its Associate Degree programs established, is planning to expand its curriculum to include Bachelor Degrees.

Use a comma or commas to set off phrases expressing contrast.

Examples: Walters State needs more parking, less grass.

The Writing Lab, not the computer lab, is where a student can find writing help.

English tutors can help with writing skills, not proofreading.

Use commas between items in a series and between coordinate adjectives.

Place commas between all elements of a series which are of equal importance.

Example: English tutors can assist students with commas, format, and citations.

Use commas according to convention in dates, addresses, place names, and long numbers.

Dates: April 27, 2007, is the last day of school for students at WSCC.

Addresses: Morristown, Tennessee, is home to Walters State Community College.

Note: Do not forget to offset the year of the date and state of the address with a comma from the rest of the sentence.

Long numbers: Current tuition at WSCC is only $1,190.50 and is one of the lowest tuitions in the state.

Use commas with quotations according to standard practice.

A signal phrase identifies the source of a quotation and can come before, after, or in the middle of a quotation. The signal phrase must be separated from the quotation by commas.

Example: Eleanor Roosevelt said, "You must do the thing you think you cannot do."

Note: No comma is needed when a signal phrase follows a quotation ending in an exclamation point or a question mark. Also, place commas that follow quotations within the quotation marks.

Use commas to prevent misreading.

In some sentences, words may run together in unintended and confusing ways, unless they are separated by a comma.

Unclear: Soon after the WSCC library closed its doors.

Clear: Soon after, the WSCC library closed its doors.

Use commas only where required.

Overusing commas can cause sentences to become choppy and confusing. This can interrupt the flow of the paper.

Common misuses:

• Don't use a comma after a subject or verb.
• Don't separate a pair of words, phrases, or subordinate clauses joined by and, or, or nor.
• Don't use a comma after and, but, although, because, or another conjunction.
• Don't set off essential elements.
• Don't set off a series from the rest of the sentence.
• Don't set off an indirect quotation or a single word that is an essential appositive.