Parallel Structure

Parallel structure means using the same pattern of words to show the two or more ideas have the same level of importance.  This can happen at the word, phrase, or clause level.  The usual way to join parallel structures is with the use of coordinating conjunctions such as "and" or "or."

Words and phrases
Words and phrases can be joined with either the –ing form (called a gerund) or the infinitive form.  Review the following examples:

Not Parallel: Mary likes hiking, to swim, and biking.
Parallel with –ing: Mary likes hiking, swimming, and biking.
Parallel with the infinitive:  Mary likes to hike, to swim, and to bike.
OR
Mary likes to hike, swim, and bike.
Clauses
A parallel structure that begins with a clause must keep using clauses.  Changing to another pattern or changing the form of the verb with break the parallelism.
Not Parallel: The coach told the players that they should get a lot of sleep, that they should not eat too much, and to do some warm-up exercises before the game.
Parallel: The coach told the players that they should get a lot of sleep, that they should not eat too much, and that they should do some warm-up exercises before the game.
OR
Parallel: The coach told the players that they should get a lot of sleep, not eat too much, and do some warm-up exercises before the game.

Lists after a colon or bulleted lists
Be sure to keep all the elements in a list in the same form.
Not Parallel: The dictionary can be used for these purposes: to find word meanings, pronunciations, correct spellings, and looking up irregular verbs.
Parallel: The dictionary can be used for these purposes: to find word meanings, pronunciations, correct spellings, and irregular verbs.

Try these proofreading strategies

  • Skim your paper for the words "and" and "or."  Check on each side of these words to see if the joined items are parallel.
  • If you have several items in a list, put them in a column and evaluate the first words to see if they're parallel. 
  • Listen to the sounds of the words in a list or comparison.  For example, do you hear an –ing word beginning each item?  Or a "to"?