Comma Rule No. 2—Separating Items in a Series
Use Commas to Separate Three or More Details, Never Two
Oct 18, 2009
One-Word Items
Items that consist of a single word are easy to separate. Place a comma after each item in the series except the last item:
- Moe, Larry, and Curly were the Three Stooges.
Also, do not place a comma before the first item in the series:
- The Three Stooges were Moe, Larry, and Curly.
Some style manuals insist that a comma must follow the second-to-last item in the series; others do not. Thus, the above sentence can also be written as
- The Three Stooges were Moe, Larry and Curly.
Coordinating Conjunctions
Whether a comma follows the second-to-last item or not, the final item should be separated with a coordinating conjuction such as and or or:
- You may buy fruit, salad, or dessert. You do not have enough money for all three.
For effect, writers sometimes omit the conjunction. This, however, should be done sparingly:
- Mike wasn't sure what he wanted: fruit, salad, dessert. They all looked tempting.
Items That Consist of More Than One Word
Complications set in when items contain more than one word:
- After getting off work, Steve drove to the bank, withdrew fifty dollars, went to the store, and bought pork chops and vegetables.
This sentence includes four items, each representing something Steve did:
- drove to the bank
- withdrew fifty dollar
- went to the store
- bought pork chops and vegetables
Using a technique called parallelism, the writer can express each item in the same way. In this case, each item begins with a verb (drove, withdrew, went, and bought). The absence of a comma after “pork chops” and of a verb before "vegetables" indicates these are part of the same item.
Novice writers sometimes blanch at the presence of so many commas in the sentence, particularly the first one (after “work"). In truth, the number of commas in a sentence does not matter so long as each comma serves a vital purpose. The first comma, for example, separates a dependent clause from an independent clause. (For more on clauses, see Comma Rule No. 1. For additional information on commas, see Comma Rule No. 3 and Comma Rule No. 4.)
Two-Item Series
Do not use a comma to separate two items in a series:
- The Rolling Stones’ main songwriters are Mick Jagger and Keith Richards.
The no-comma rule applies even if the two items consist of phrases:
- Sarah rode her favorite horse and won a blue ribbon.
- While walking through the forest, we saw magnificent oak trees and tiny, thorny shrubs.
Notice that there is no comma after “horse” or “trees” in the above sentences. (The commas after “forest” and “tiny” serve other functions.)
Test Yourself
Are commas needed in the following sentence? (Answer appears at the end of the article.)
- Neither Margaret nor Judy has brought a pencil eraser or flash drive to class.
When determining how many commas to place in a series of items, first determine how many items are in the series, then use parallelism to make sure that the items are clearly identified. Avoid placing a comma before the first item and after the last item. (Answer: Place a comma after “pencil” if “pencil” and “eraser” are two items; otherwise, no commas.)
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