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Comma use

Apply the small set of comma rules the SAT tests, including nonessential elements and introductory phrases.

Standard English ConventionsReading and Writing
Practice comma use free

What the SAT actually asks

You decide whether a comma belongs in a specific spot. The tested rules are narrow: commas after introductory elements, commas around nonessential descriptive phrases and clauses, commas separating items in a list, and a comma before a coordinating conjunction joining two independent clauses. Just as important is knowing where a comma is wrong, such as between a subject and its verb, or around a clause that is essential to identifying what it describes.

Comma questions usually account for roughly 2 to 3 of the 54 reading and writing questions.

Where students lose points

How to attack these questions

  1. 1Try removing the phrase in question, and if the sentence still identifies its subject clearly, the phrase is nonessential and needs commas on both sides.
  2. 2Check that any comma you keep corresponds to a rule you can name, rather than to a place you would pause when speaking.
  3. 3Confirm that a comma before and or but is separating two full sentences, not just two verbs sharing a subject.

Example questions

Written for this skill, with the answer explained. 44 more are in the app.

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Comma use
Real question

The novelist ______ published her first book at nineteen and spent the next four years refusing to write a second one.

Which choice completes the text so that it conforms to the conventions of Standard English?

Easier

Which choice completes the text so that it conforms to the conventions of Standard English? The book that was published last year ______ received strong reviews.

  • A) :
  • B) (no punctuation) ✓
  • C) ,
  • D) ;

Why: "that was published last year" is restrictive: it picks out which book received the reviews, so it takes no punctuation, and "(no punctuation)" is correct. A "," would close the clause as nonrestrictive, and clauses beginning with "that" are not set off this way; with no opening comma it would also separate the subject "book" from the verb "received." A ";" needs an independent clause after it, and "received strong reviews" has no subject. A ":" announces a list or explanation and would likewise cut the subject off from its verb.

Medium

Once the last layer of volcanic ash had been lifted from the floor of the room with brushes and a vacuum no wider than a ______ the mosaic beneath it turned out to have lost only one tessera from the whole of its border.

Which choice completes the text so that it conforms to the conventions of Standard English?

  • A) finger
  • B) finger;
  • C) finger:
  • D) finger, ✓

Why: Everything before the blank is a subordinate clause beginning with "Once," and a comma is what separates it from the main clause that follows. "finger" omits that comma, letting the long introductory clause run straight into the subject of the main clause. "finger;" puts a semicolon after a dependent clause, but a semicolon needs an independent clause on each side and the clause beginning "Once the last layer" is not one. "finger:" puts a colon after that same dependent clause rather than after a complete one, which a colon requires.

Harder

The surveyors finished the eastern traverse in a single week of clear ______ and the western traverse across four ravines and a stretch of low ground that floods every spring took them the better part of two years and three changes of instrument to complete.

Which choice completes the text so that it conforms to the conventions of Standard English?

  • A) weather, ✓
  • B) weather:
  • C) weather
  • D) weather;

Why: The western traverse across four ravines took them the better part of two years, and that clause has its own subject and verb, so "and" is joining two independent clauses and needs a comma before it. "weather:" is wrong because a colon cannot stand before a coordinating conjunction like "and." "weather" omits that comma, and the long subject of the second clause makes the missing comma easy to miss. "weather;" uses a semicolon in addition to the conjunction that is already joining the clauses, which is redundant since a semicolon replaces a conjunction rather than accompanying one.

Questions students ask

When do I use commas around a phrase?

Use a pair of commas when the phrase adds extra information that could be removed without changing what the sentence identifies. If removing it would leave the reader unsure which person or thing is meant, the phrase is essential and takes no commas.

Should I put a comma wherever I would pause?

No. Pausing is not a rule, and it produces commas between subjects and verbs, which is always wrong. Every comma on the SAT should correspond to a specific rule, such as an introductory element, a list, a nonessential phrase, or joining two independent clauses.

Do I need a comma before and in a list?

The SAT uses the serial comma before the final and in a list of three or more items. You will not be asked to choose between including it and leaving it out as the only difference, but the correct answers are written with it.

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