Reading & WritingSentence BoundariesMedium frequency

SAT Reading & Writing: Use em dashes correctly for emphasis or interruption

23+ practice questions in Praczo

What you need to know

The concept, explained

  • 1

    An em dash — like this — can mark a sharp interruption, emphasis, or a nonessential phrase in the middle of a sentence.

  • 2

    When em dashes set off a nonessential phrase, they must come in a matched pair: one dash opens it, one closes it. You cannot mix a dash with a comma or parenthesis to close.

  • 3

    A single em dash at the end of a clause can introduce a sudden emphasis or explanation — like an informal colon.

  • 4

    Do not use an em dash to join two independent clauses the way a semicolon or period does, unless emphasis is needed — otherwise, use standard punctuation.

Common mistakes
  • Mixing an em dash with a comma to bracket a nonessential phrase (e.g., "The project — funded by the town, was delayed"). Use two dashes or two commas, not one of each.
  • Overusing em dashes when commas or a colon would be clearer.
Try a sample question

SAT-style practice

Which choice best completes the sentence? "The new bridge — completed ahead of schedule _____ has already become the town's most photographed landmark."

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