Elsewhere on this site, we discuss the importance of parallel structure in vertical (bulleted) lists. But two or more parts of a sentence, clause, or phrase should be grammatically parallel even without bullets (or numbers or letters). This article focuses on parallel structure in embedded lists.

Coordinating Conjunctions

Coordinating conjunctions—for, and, nor, but, or, yet, so (see more about the FANBOYS in this article)—signal the need for parallel structure. That is, two or more items (words, phrases, or clauses) connected by those conjunctions should have the same logical and grammatical construction.

Here’s a sentence using and to coordinate two thoughts:

When he saw the results of her work, he wanted to know which cases she had read and which sources she had consulted.

Note that the two coordinated parts are parallel: they are both answer the question “to know what?” (Grammatically, they are noun clauses functioning as objects of the infinitive “to know.”)

Had the sentence contained an error in parallelism, it might have looked like this:

When he saw the results of her work, he wanted to know which cases she had read and her sources.

Now the noun clause “which cases she had read” is being inappropriately coordinated with the noun phrase “her sources,” and the sentence is neither as easy to understand nor as memorable as it would be if each item in the pair were parallel with the other.

Helpful Strategy

To make the items in a list parallel, it is helpful to consider exactly where the list begins.

Once we separate the introduction to the list from the list itself, we can more easily notice whether the items are parallel by testing each item in the list as if it were the only item following the introduction—that is, as if there were not a list but a single item.

Let’s examine, for example, this sentence:

We bought a house in town to ensure a shorter daily commute, access to better schools, and to be close to restaurants.

If the introduction to the list is “We bought a house in town to ensure. . . ,” then what follows the introduction–the list itself–looks like this:

• • • a shorter daily commute
    • access to better schools
    • to be close to restaurants

The first two items logically follow “We bought a house in town to ensure . . . ,” but the last one does not. The first two logically answer the question, “To ensure what?” They are noun phrases serving as objects of the infinitive “to ensure.”  

But the third item is an infinitive phrase, and what we end up with is this awkward attempt at a sentence:

We bought a house in town to ensure to be close to restaurants.

To make our list parallel, we could make all three items noun phrases logically following the infinitive “to ensure”:

• • • a shorter daily commute
    • access to better schools
    • proximity to restaurants

We could decide instead, though, that the introduction stops before the infinitive “to ensure”: if our introduction is “We bought a house in town . . . ,” now our list looks like this:

• • • to ensure a shorter daily commute
    • access to better schools
    • to be close to restaurants

Now the item that doesn’t make sense behind the introduction is the second one because when we add it to the introduction, we end up with this ungrammatical construction:

We bought a house in town access to better schools.

To make our list parallel, we can either make all three items noun phrases (that is, put the infinitive in the introduction, as we did in our initial revision above) or make all three infinitive phrases (by adding “to have” to the second item). 

Why Bother with Parallel Structure?

First, our writing reflects our thinking; readers may assume we are sloppy thinkers if our writing is not logical.

Second, when text is grammatically parallel, it is more memorable. Just as it is easier to remember passages that rhyme or have consistent rhythm, it is easier for our brains to recall information that is expressed in parallel form.

Finally, parallel structure enhances both the sophistication and the professionalism of our writing.

Parallel structure is important not only in embedded lists with coordinating conjunctions but also with bulleted lists and correlative conjunctions. The latter will be the subject of the next new article on this site. This type of conjunction sometimes trips up even the most seasoned writers. If you aren’t already a newsletter subscriber, sign up now so you’ll be the first to know when that article is posted.

Test Yourself

Identify and correct problems with parallel structure in the following sentences containing embedded lists with coordinating conjunctions:

1. 1. The chief executive officer manages acquisitions, mergers, and reports to the board of directors quarterly.
   2. Time spent on artistic endeavors can be energizing, relaxing, or it can be both.
   3. Walking daily is a helpful strategy for physical fitness, mental health, and for appetite control.
   4. If we look beyond our own narrow self-interest during the COVID-19 pandemic, we (1) will be vaccinated, (2) wear masks any time we are inside, and (3) will keep our distance from one another, yet the failure of many people to do so has led to the senseless deaths of hundreds of thousands of people.
   5. The judges examined each artwork for its compositional integrity, use of color, and its treatment of light.

Answers

1. The chief executive officer manages acquisitions and mergers and reports to the board of directors quarterly.

Here we have two different pairs: the first pair is a pair of nouns, acquisitions and mergers, and the second is a pair of verbs, manages and reports. A common mistake is for writers to confuse two separate pairs and attempt to treat them as a single list of three or more items.

2. Time spent on artistic endeavors can be energizing, relaxing, or both.

The original list of three items joined by or included two adjectives, “energizing” and “relaxing,” and one clause “it can be both.”

OR:  Time spent on artistic endeavors can be energizing, it can be relaxing, or it can be both.

This list a list of three clauses. Again, the repetition can be a stylistic strategy.

3. Walking daily is a helpful strategy for physical fitness, mental health, and appetite control.

The original repeated the preposition “for” in the third item but not in the second. It would have been fine to repeat it all three times (for emphasis), but in this correction we took it out, considering the initial “for” to be part of the introduction to the list and, thus, applicable to all three items.

4. If we look beyond our own narrow self-interest during the COVID-19 pandemic, we will (1) be vaccinated, (2) wear masks any time we are inside, and (3) keep our distance from one another, yet the failure of many people to do so has led to the senseless deaths of hundreds of thousands of people.

This list consists of three verb phrases: be vaccinated, wear masks, and keep our distance.

OR:  . . . we will ensure that we are (1) vaccinated, (2) masked any time we are inside, and (3) distant from one another 

This list consists of three participles (adjectives): vaccinated, masked, and distant.

OR:  (1) we will be vaccinated, (2) we will wear masks any time we are inside, and (3) we will keep our distance from one another 

This list consists of three clauses. Some would consider this construction wordy, but sometimes repeating phrases achieves greater emphasis.

Note, too, the use of numbers with this embedded list. Numbers and letters (though not bullet points) are perfectly fine to use in embedded lists and in fact can enhance readability in long lists. Keep in mind, however, that despite what word processing software programs say, parentheses always come in pairs, so use a parenthesis both before and after the number or letter.

5. The judges examined each artwork for its compositional integrity, its use of color, and its treatment of light.

Here the list comprises three noun phrases, each starting with a possessive pronoun. While this list is now parallel, some would find it wordy and may choose instead to make the possessive pronoun “its” part of the introduction, thus:

The judges examined each artwork for its compositional integrity, use of color, and treatment of light.

The next new article on this site will address parallel structure with correlative conjunctions, including “not only . . . but also,” “either . . . or,” and so forth. Become a subscriber to be among the first to know when it’s published.

I address parallel structure in the second online course of the three-part series called Pro Tips for Professionals. “Logic, Clarity, and Precision” tackles parallel structure and a host of other constructions. Newsletter subscribers receive regular discounts on all online asynchronous courses.

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