Whenever our writing includes a list, the items in that list need to be parallel with one another. That is, all of the items in a list must be the same, both logically and grammatically.
Logically Parallel Lists
First, the items in a list must be parallel in meaning. Writers sometimes think that anything related to the topic at hand is fair game in a list, but it is jarring to a reader to find an item on a list that is not logically consistent in meaning with the other items in that same list.
If, for example, we are listing a city’s curfew rules, the penalty for violating those rules would not logically belong in that list.
Or consider this list, which lacks logical parallel meaning:
Widgets for the World has developed a marketing campaign to reach key sales objectives:
- To grow our share of the U.S. widget market by 10 percent over the next year.
- To increase widget sales in the E.U. by 5 percent.
- To open widget markets in Canada.
- Emily Jones will oversee this campaign.
- The campaign will launch on April 10.
If we tell our reader we are going to list the objectives of a forthcoming marketing campaign, that list should not include the point person or the kick-off date.
Grammatically Parallel Lists
Even if all five items in our widget marketing campaign list above were logically consistent, the list would still be lacking in parallel structure.
To be parallel, all the items in a list need to have the same grammatical form. The Widgets for the World list starts out with three parallel infinitive phrases (to grow, to increase, and to open), but it concludes with two sentences.
A parallel list might consist of
- all single words of the same part of speech (all nouns, all adjectives, all verbals, etc.),
- all phrases of the same structure (all infinitive phrases, all “-ing” verbal phrases, all noun phrases, or all prepositional phrases),
- all subordinate clauses, or
- all main clauses (sentences).
Single words (nouns):
College students find that in addition to tuition, room, and board they must be able to finance other expenses including
- transportation, and
Businesses are better able to retain employees who are given
- flexible schedules,
- adequate vacation,
- comprehensive health care benefits, and
- substantial retirement benefits.
Other phrases of the same structure (in this example, gerund phrases):
Let your doctor know if your child is not performing any of the following tasks at the same rate as other children the same age:
- identifying shapes, colors, and familiar objects;
- speaking or putting together phrases and sentences;
- maintaining balance and coordination;
- paying attention; or
- following directions and remembering information.
Dependent clauses (in this example, relative clauses):
The press noted repeatedly that the jury consisted solely of people
- who had completed at least one year of education beyond high school,
- who had annual income in excess of $60,000,
- who had lived in the Houston area for at least ten years.
Main clauses (complete sentences):
Cybil’s speech contained at least three clichés:
- “A watched pot never boils.”
- “Look before you leap.”
- “The early bird gets the worm.”
Parallelism Is Important Even without Bullets
Often we use bullets or numbers to draw attention to lists, but coordinated parts of a sentence, clause, or phrase should be parallel even when there are no bullets or numbers. (We have another article on punctuation and formatting for lists with bullets and numbers, also known as vertical lists.)
Parallelism with Coordinating Conjunctions
The coordinating conjunctions (and, but, or, nor, for, so, and yet) signal the need for parallel structure. That is, the items (words, phrases, or clauses) connected by those conjunctions—whether or not we use bullets—should have the same logical and grammatical structure.
Here is a sentence that uses the conjunction and to coordinate two thoughts, highlighted here with italics:
- When he saw the results of her work, he asked to see what cases she had read and what sources she had consulted.
Note that the two coordinated parts—“what cases she had read” and “what sources she had consulted”—are parallel; that is, they are both noun clauses functioning as objects of the infinitive “to see.” Had the sentence been poorly written (i.e., contained an error in parallelism), it might have looked like this:
- When he saw the results of her work, he asked to see what cases she had read and her sources.
Now the noun clause “what cases she read” is being 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.
Parallelism with Correlative Conjunctions
The correlative conjunctions are pairs of words that hold together two concepts that should be parallel both grammatically and logically. They are either X or Y, neither X nor Y, both X and Y, not X but Y, and not only X but Y [or but also Y].
Consider this sentence that lacks parallel structure:
- These unprecedented times are affecting not only those of us here in the United States but also are clearly having a global impact.
This writer has illogically used the correlative conjunction not only X but also Y, pairing a group of people (“those of us here in the United States”) with a verb phrase (“are clearly having a global impact”).
What the writer likely intended to compare were two groups of people: “These unprecedented times are affecting not only those of us here in the United States but also people around the world.”
Or the writer could have chosen to compare two actions instead: “These unprecedented times are not only affecting those of us here in the United States but also wreaking havoc around the world.”
With correlative conjunctions, the same grammatical and logical construction should follow both parts of the conjunction—in these examples, the pronoun those pairs both logically and grammatically with the noun people, and the present participle affecting pairs with wreaking.
Parallelism with Semicolons, Colons, and Periods
Many famous quotations are easy to remember and recite precisely because the parts that are parallel in meaning are also parallel in grammatical structure:
- “I have a dream that my four little children will one day live in a nation where they will be judged not by the color of their skin but by the content of their character.” ―Martin Luther King, Jr.
- “Be who you are and say what you feel because those who mind don’t matter, and those who matter don’t mind.” ―Bernard M. Baruch
Sometimes writers produce memorable expressions with two grammatically parallel clauses, one following the other but without conjunctions:
- “Ask not what your country can do for you; ask what you can do for your country.” —John. F. Kennedy
- “If you want others to be happy, practice compassion. If you want to be happy, practice compassion.” —Dalai Lama
- “Success is getting what you want. Happiness is wanting what you get.” —Dale Carnegie
- “We make a living by what we get; we make a life by what we give.” —Winston Churchill
Why Bother with Parallel Structure and Meaning?
First, logical parallelism is important because our writing is a reflection of our thinking. Whether consciously or unconsciously, our readers will perceive us to be 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, passages that are parallel are easier for our brains to recall, as with the famous passages cited above.
Finally, parallel structure enhances both the sophistication and the professionalism of our writing. Text that is parallel logically and grammatically is easier to read and to remember.
Identify and correct errors in parallel structure in the following sentences:
- The extended warranty explains these services and who delivers them.
- The book discusses how to build a profitable stock portfolio and saving for college tuition expenses.
- The company’s quarterly meetings consisted of reviewing the previous meeting’s minutes, hearing a financial report, and the president’s plans for future expansion.
- The lifesaving course will focus either on water safety issues or how to administer CPR.
- He gave a gift to his mother, his father, his grandmother, and to his grandfather.
ANSWERS (parallel parts are underlined and conjunctions are in italics)
- The extended warranty explains these services and specifies who delivers them. OR: The extended warranty explains what these services are and who delivers them.
- The book discusses how to build a profitable stock portfolio and how to save for college tuition expenses. OR: The book discusses building a profitable stock portfolio and saving for college tuition expenses.
- The company’s quarterly meetings consisted of reviewing the previous meeting’s minutes, hearing a financial report, and presenting the president’s plans for future expansion. OR: The company’s quarterly meetings consisted of a review of the previous meeting’s minutes, a financial report, and the president’s plans for future expansion.
- The lifesaving course will focus on either water safety issues or CPR. OR: The lifesaving course will focus either on water safety issues or on CPR. OR: The lifesaving course will focus on either how to ensure water safety or how to perform CPR.
- He gave a gift to his mother, his father, his grandmother, and his grandfather.
Copyright 2002 Get It Write. Revised 2020.