Parallel Structure

1. Parallelism in Sentences

When talking about writing, it’s useful to imagine sentences as being constructed or made up of building blocks. These blocks can be put together strongly or weakly, and that construction will influence how clear a sentence is.

Think about parallel construction in a sentence. While you may have heard the word "parallel" used a bit differently in a math course, here we use it to mean "matching." All the words and phrases inside the sentence need to be structured so that they are parallel; this is a strong way of building a sentence.

Thus, parallelism is the use of repeating grammatical structures to highlight similarities between ideas.

EXAMPLE

I like to sing, to dance, and to swim.

Notice how in that list, each of the verbs is in its infinitive form, meaning each begins with the word "to." What if the form of one of those verbs changed?

EXAMPLE

I like singing, to dance, and to swim.

Here, "singing" has been changed to the present tense, but "to dance" and "to swim" haven’t been. Though the meaning hasn’t necessarily changed fundamentally, the sentence is much harder to understand, and the construction is weak overall.

As you can see, a lack of parallelism is not just grammatically incorrect; it’s also confusing for the reader. Especially with lists of verbs, you need to be careful to match tense and number.

term to know

Parallelism

The use of repeating grammatical structures to emphasize similarities between ideas.

2. Correcting Parallelism Errors

Now that you know what parallelism is, it's important to be able to identify and correct errors related to parallelism.

Take a look at this sentence describing Phil’s family and see if you can spot the parallelism error:

EXAMPLE

Everybody in Phil's family hates to read and playing cards.

As you probably figured out, this sentence isn’t correct because "to read" is in the infinitive tense, but "playing cards" is in the present tense. To correct this sentence, you can simply change one of the verbs to match the other:

Everybody in Phil's family hates reading and playing cards.

Now consider this sentence, which includes a list of adjectives instead of verbs:

EXAMPLE

The dungeon was cold, damp, and it was uncomfortable.

The list starts off well— "cold" and "damp" are parallel because their structures match. But then the way the list is put together changes, and the third item is "it was uncomfortable." This is where the sentence stops being parallel. But this is easily fixed, too:

The dungeon was cold, damp, and uncomfortable.

What about the list of nouns in this sentence:

EXAMPLE

I wanted to travel in Spain, Italy, and in Portugal.

The error is small, but it's there. All you have to do is pop in another "in" to make the second item match the rest:

I wanted to travel in Spain, in Italy, and in Portugal.

Let's try one more:

EXAMPLE

I wanted to travel to Los Angeles and to San Francisco in California, as well as Memphis and Nashville in Tennessee.

This one is a little harder because each pair matches on its own, but the two sets don’t match each other. Thus, the sentence is not parallel. Adding the word "to" helps create parallelism:

I wanted to travel to Los Angeles and to San Francisco in California, as well as to Memphis and to Nashville in Tennessee.