​

Using parallel structure shows that two or more ideas have the same degree ​of importance. In essence, it helps maintain clarity because parallel sentences are easier to understand.

​​What is Parallel Structure?

Parallel structure (or parallelism) means using the same grammatical form or word pattern in two or more parts of a sentence. It is most commonly seen in lists of two or more items.

 

The subjects complained of difficulties including falling asleep, waking up with nightmares, and to experience sleeplessness.

 

This sentence is not parallel because the last item in the list (“to experience sleeplessness") does not match the verb form of the first two items in the list (“falling asleep" and “waking up").

 

The subjects complained of difficulties including falling asleep, waking up with nightmares, and experiencing sleeplessness.

 

The sentence is parallel now, because all three items in the list begin with verbs in the same form: an -ing ending.

​Parallel structure gets more complex as items in a list become more complex.

 

The researcher told the subjects that they should get a lot of rest, that they should eat regularly, and that journaling should be done about their experiences.

 

This sentence is not parallel. The first two items are in active voice, but the last item in the list is written in passive voice (see Active vs. Passive Voice). Another way to think about this is, the first two items begin with “they" (the subjects) and then the recommended activity. The last item begins with the activity.

 

The researcher told the subjects that they should get a lot of rest, eat regularly, and journal about their experiences.

 

This version of the sentence is parallel. The sentence is also clearer and more concise.​​​​​

How Can I​​ Fix Parallel Structure Problems?

Li​​​sts

  1. Identify a sentence with a list.
  2. Check each item in the list to see if they are all formatted in the same way. Reading the sentence aloud can help with this, as we can often hear errors that our eyes don't see.
  3. Edit so that all items in the list are parallel: following the same pattern or the same form.

He​adings

​Parallel structure is also important when using headings within a document. Headings at the same level should be parallel to one another.​​
  1. Look at headings together as a group or as an outline.
  2. Check comparable headings, or headings at the same level.
  3. Edit to make sure all headings are parallel.

For example,

​Researcher's Experience
Concerns of the Researcher
Researcher's Hypotheses 

These headings are not parallel. The second heading does not follow the pattern of the first and third. Editing is needed for parallel structure. 

Researcher's Experience
Researcher's Concerns
Researcher's Hypotheses

​​Additional Resources