Correct Comma Usage in a List of Adjectives

Coordinate Adjectives Need a Comma

• If the nouns preceding the comma are both used in the same way (what grammarians call coordinate adjectives), separate them with a comma. Coordinate adjectives can be:

  • Interchanged. You can reverse their order without affecting readability or meaning.
  • Separated by "and."

  Let's look at the above example: "I found an honest reliable mechanic."

  • You can write "a reliable honest mechanic."
  • You can separate the adjectives with and: a reliable and honest mechanic.

  Thus, the proper way to write this sentence is: "I found an honest, reliable mechanic."

Non-Coordinate Adjectives Do Not Need a Comma

• If adjectives modify nouns in different ways (non-coordinate adjectives), do not separate them with commas. If you cannot switch the order of the adjectives and cannot separate them with the word "and," do not use commas between them.

  For example, you buy a puzzle at the thrift shop and write: "I bought an unopened jigsaw puzzle."

  "Unopened" and "jigsaw" represent different attributes of the puzzle. "Unopened" describes the puzzle's condition, while "jigsaw" describes, fundamentally, the type of puzzle.

  You would never write: "I bought a jigsaw used puzzle." Or: "I bought I used and jigsaw puzzle."

More Examples

• Consider these additional examples of coordinate adjectives — the type that need a comma:
  • She is an outgoing, friendly dog. (The dog is outgoing and friendly.)
  * He is a smart, happy child. (The child is smart and happy)

  Consider these examples of non-coordinate adjectives — the ones that don't need a comma:
  • He opened the old iron gate.
  • The bright harvest moon shone down.

Where to Look for Help

• If you are concerned about proper punctuation, consider investing in a good reference book. A comprehensive reference of grammar, usage and style is "Garner's Modern American Usage." A reference used by college freshman throughout the country is "The Hodges Harbrace Handbook" or "The Writer's Harbrace Handbook." If you don't want to invest in a printed handbook, you can consult many online references for information about punctuation and grammar. Some universities provide online guides that are accessible to everyone. One such site is the Purdue University Online Writing Lab — or "Purdue OWL." This site provides easy-to-follow, comprehensive guides at http://owl.english.purdue.edu/owl/section/1/. See the Resources section below for additional online references.