What is Parallel Sentence Structure?

Writers often wonder about this question: What is parallel sentence structure? Parallel sentence structure is a grammatical structure in a sentence where two or more items are grammatically identical. It is important for writings to contain parallel sentences because parallelism contributes to a better and easier understanding of the material at hand. Sentences that are not parallel confuse readers as the sentences lack flow and readability. Parallel sentences are sometimes called balanced sentences.

Parallelism in Writing

Writers can achieve parallelism in writing by ensuring that certain items in their writings are parallel. For example, it is important that nouns, verbs, phrases, and clauses are parallel in writings. The following sections will discuss how to create parallelism in writings, provide balanced sentence examples, and show parallelism in writing examples.

Parallel Nouns

One of the elements in a parallel sentence is the parallelism of nouns. Nouns in a sentence must be parallel i.e., they must be all singular or all plural. The following table shows examples of sentences without parallel nouns as well as correct sentences containing parallel nouns.

• Correct: Mexicans, Peruvians, and Colombians speak Spanish.
  • This example shows the correct parallelism of nouns. All the nouns in this sentence are plural.

Parallel Verbs

It is important for writers to ensure that the verbs in their writings have a parallel structure. One common mistake that writers make is to have both gerunds (verb plus -ing) and infinitives ( to plus verb) in the same sentence. Instead, sentences must use only gerunds or only infinitives.

The table below explains parallelism grammar rules regarding parallel verbs in sentence examples.

An example of parallel verbs.

Parallel Conjunctions

Coordinating conjunctions and correlative conjunctions are some of the most important markers of parallelism in sentences. It is important that the two items on either side of the conjunctions be parallel. For, and, nor, but, or, yet, and so are coordinating conjunctions. Either/or, neither/nor, both/and, and not only/ but also are correlative conjunctions.

• James Baldwin was not only a novelist but also an essayist.
  • In this sentence, the elements on either side of the coordinate “but” are parallel: a novelist and an essayist. The correlative conjunction in this sentence is not/only but/ also.
• Incorrect: James Baldwin was an essayist, and he was politically active too.
  • This sentence lacks parallelism. Thus, it is wrong. The two elements on either side of the coordinating conjunction and are not parallel. An essayist is a noun, and he was politically active is an independent clause. The correct sentence is: James Baldwin was an essayist and (an) activist. Or James Baldwin wrote essays and participated in political activities.

And is a coordinating conjunction.

Parallel Phrases

Sometimes a sentence has more than one phrase (a group of words). It is essential that all the phrases in a sentence be parallel. By ensuring that all the phrases have the same parts of speech and grammar structure, writers can create parallel phrases.

• A teacher is responsible for teaching students, correcting exams, and preparing lessons.
  • In this sentence, all three phrases teaching students, correcting exams, and preparing lessons are parallel. All the phrases consist of a gerund and a plural noun.
• Incorrect: In a thesaurus, synonyms for words, word antonyms, and definitions are easily found.
  • This example lacks parallelism because synonym for words, word antonyms, and definitions are not parallel. This sentence can be reworded correctly as: In a thesaurus, word synonyms, word antonyms, and word definitions are easily found. To make the sentence easier to read, it can be reworded as: In a thesaurus, word synonyms, antonyms, and definitions are easily found.

Parallel Clauses

Some sentences contain several clauses connected to each other by a coordinate conjunction. One way to ensure that clauses are parallel is to check if they are all following the same grammatical pattern.

• Single parents usually have busy schedules; they feed their children, they drive the children to school, and they go to work.
  • In this example, three clauses they feed their children, they drive the children to school, and they go to work are independent clauses connected to each other by the coordinating conjunction and. Therefore, the clauses in this sentence are parallel.
• Incorrect: The boss comes in the office, looking around, and she found her folder on the desk.
  • This sentence lacks parallelism of clauses. The first clause, the boss comes in the office, is an independent clause in the present tense (comes). Looking around is a phrase. She found her folder is an independent clause with the verb, found, in the past tense. The sentence can be corrected as: “The boss comes in the office, she looks around, and she finds her folder on the desk.” Or, “The boss came in the office, she looked around, and she found her folder on the desk.”

Parallel Items in a Series

When listing items in a series, parallel sentence structure is commonly used. The parallel structure when listing items in a series usually underscores the verb tenses that agree. The following are examples of parallelism in writing:

• Latisha and her friends will go to the zoo, (will) feed the animals, and (will) take many pictures.
  • This sentence is correct because the items in the series are parallel. Will go, (will) feed, and (will) take are all verbs in the future tense.
• Incorrect: The prime minister has visited several countries in Asia, has met with her counterparts, and ate Asian dishes.
  • This sentence is incorrect because it lacks parallel structure. Both has visited and has met are present perfect, but ate is simple past. The sentence can be corrected as: “The prime minister has visited several countries in Asia, has met with her counterparts, and has eaten Asian dishes.” However, the sentence can flow better and sound more natural this way: “The prime minister has visited several countries in Asia, met with her counterparts, and eaten Asian dishes.”

Parallel Comparisons

When comparing two elements in a sentence, the two elements must be parallel. The following are examples of parallelism in writing:

• Some professors like teaching undergraduate courses more than teaching graduate courses.
  • This example is comparing two elements of teaching undergraduate courses and teaching graduate courses. Both elements are shown in the form of gerunds.
• Incorrect: I prefer to drive my car more than washing it.
  • This sentence is wrong because the comparison is shown with an infinitive, to drive and a gerund, washing. The correct sentence is: I prefer driving my car more than washing it.

How to Make a Sentence Parallel

It is always a good practice for writers to proofread their work before handing it in. Writers need to assure that sentences follow parallelism rules. For example, they need to remember the verbs in one sentence must have the same tense, such as they are all in present perfect, or they are all in passive voice. Also, gerunds and infinitives together do not constitute a parallel structure.

The following steps show how to make a sentence parallel.

• The first step is to identify coordinating conjunctions, such as and, or, and but.
• The second step is to identify correlative conjunctions, such either/or and neither/nor.
• Third, writers need to ensure that the items on either side of the conjunctions are parallel.
• Last, the structures that are not parallel must be rewritten.

Lesson Summary

Writings are more effective and easier to read when they contain parallel structures. Parallelism in a sentence can be applied to nouns, verbs, phrases, and clauses. In addition, in comparisons, both items must be parallel. Usually, parallel structures are formed around coordinate conjunctions, such as and, for, but, and so as well as correlative conjunctions like neither/nor and either/or.

Writers need to edit their work to make the items on either side of the conjunction parallel. For example, writers need to ensure that both items on either side of a conjunction are either all gerunds or all infinitives. Alternatively, if items form a series of nouns, they all have to be either singular or all plural. Parallel structure in a series often highlights verb tenses that agree.