Introduction to Parallel Structure in English

Parallel structure in English refers to the use of similar grammar constructions within a sentence or clause. Understanding parallel structure in English can help your TOEFL score.

Examples of parallel structure

Parallel structure is a fairly advanced grammar concept. But examples of good and bad parallel structure can be surprisingly obvious. So before we go into the exact definition of parallel structure, let me show you some sample sentences. Read the pairs of sentences below. Can you tell which sentence is best?

Sentence Pair A:

1. I like to eat apples and drinking apple juice too.
2. I like to eat apples and to drink apple juice too.

Sentence Pair B:

1. I am taking the bus and went to school.
2. I took the bus and went to school.

Sentence Pair C:

1. The raccoon and skunks are animals found primarily in North America.
2. The raccoon and skunk are animals found primarily in North America.

You may have already sensed the “good” sentence in each of the pairs above. But if you’re still not sure, don’t feel bad. Like I said, this is an advanced English concept. We’re about to look at it in detail.

In each of the sentence pairs above, the second sentence is the better one. The second sentence is the one with parallel structure. Each #2 sentence has matching pairs of verbs or nouns. In Pair A sentence 2, to eat and to drink are both infinitive verb forms. So the grammar structures of these verbs are the same — the structures are parallel. In sentence 2 of Pair B, took and went also show parallel structure; both are past tense verbs. Finally, in sentence C2, we see both nouns in the singular with “the” used to label the nouns and broad categories. (See Rule 6 in my post on using “the” in English.)

In contrast, each of the first sentences do not have parallel structure. In Pair A sentence 1, to eat is infinitive, while drinking has an -ing ending and is present participle. In Pair B sentence 1, am taking is present progressive tense, but went is simple past tense. Finally, in Pair C sentence 1, the raccoon is singular and marked with “the,” while skunks is plural.

The rules of parallel structure in English

Obviously, the most important rule of parallel structure is that it requires two or more verbs or nouns to have the same grammatical form. But under what conditions must verbs or nouns have parallel grammar structure?

Rule # 1: Parallel structure requires that nouns and verbs have the same grammatical form

This is the most obvious feature of parallel structure, as seen and explained with the examples above. Parallel structure nearly always applies only to verbs that are used together or nouns that are used together. This is because verbs and nouns have some clearly different grammatical forms. Verbs have tense, participle, and singular/plural variations. Nouns can be singular or plural, and can have determiners (words like a, an, and the) attached to them.

Rule # 2: Parallel structure should be used within a single clause.

Generally, two or more verbs or nouns must be parallel if they’re in the same clause. Recall that a clause is a set of words that has a subject and predicate. (Predicates add information about a subject and must contain a verb.) Some clauses are complete sentences. Other clauses are phrases within a complete sentence.

• A complete sentence clause with parallel structure:
• The car won’t drive or even start.
• (Drive and start are both simple present verbs. If you instead said something like “The car won’t be driving or even start,” you would break parallel structure.)
• A phrase clause with parallel structure (the clause portion of the sentence is in bold):
• He couldn’t get to work with his car not driving or starting.
• (Driving and starting are both present participle verbs. It would not be acceptable to write “his car not driving or started.”)

Rule # 3: Parallel structure is often used with verbs and nouns that are joined by conjunctions.

Conjunctions are words that join two clauses or join multiple nouns and verbs. For a list of conjunctions in English, see Kate’s post “TOEFL Grammar: Using Conjunctions.” If you’re using conjunctions, this may be a sign that you need to use parallel structure. Here are a few examples of conjunctions that connect verbs or nouns with parallel structure:

• He’s working hard while earning lots of money.
• (While connects the parallel verb forms working and earning.)
• Active volcanoes may spew smoke, ash, and sometimes lava.
• (And connects three singular noun forms: smoke, ash, lava.)

Rule # 4: Parallel structure should only be broken for specific reasons.

Parallel structure can be broken in English. And it often is broken. But it has to be broken for a specific reason. Two common reasons to break parallel structure relate to verb tense and contrasting noun forms. Sometimes two or more verb tenses are used in to show a clear difference between events. At other times, two or more noun forms can have different grammar because the nature of the nouns is different. Here are a few examples of sentences where parallel structure is broken for good reason. All of these sentences are correct even though they don’t have parallel structure:

• Two past tense events, one of which interrupted the other (interrupted event in past continuous tense, interrupting event in simple past):
• The baby was crying, but stopped.
• Three past events that take place in the past, present, and future, and thus have three different grammar forms:
• My mom studied at university, is working now, and will retire someday.
• Using a plural form and a singular form to contrast two kinds of verbs:
• The family has three cats, not a dog.

These are just a few possible examples of acceptable breaks in parallel structure. As long as you have a meaningful reason to make a group of nouns or verbs grammatically different from each other, you can break parallel structure.

How to Use Parallel Structure on the TOEFL

Parallel structure is most important in TOEFL Writing. Mistakes in parallel structure make your TOEFL Writing essays harder to read. This can cost you points on the TOEFL. You should also make an effort to follow parallel structure in TOEFL Speaking. However, in spoken English, breaking parallel structure is more forgivable. Minor mistakes in spoken parallel structure on the TOEFL might hurt your score just a little.  But if you just make one parallel structure mistake in a TOEFL Speaking response, there’s a chance you won’t lose any points.

A good understanding of parallel structure can also boost your comprehension in TOEFL Listening and TOEFL Reading. Read or listen for parallel structures. When you encounter similar verb and noun forms in TOEFL sentences, you can know that these verbs and nouns are probably part of the same clause. This makes it easier for you to follow more complicated sentences without losing the “sense” of the sentence. It also helps to recognize breaks in parallel structure. If you notice a sudden change in verb or noun forms, you can recognize that certain actions or things are different in some way and are being contrasted.

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About David Recine

David is a test prep expert at Magoosh. He has a Bachelor of Social Work from the University of Wisconsin-Eau Claire and a Masters in Teaching English to Speakers of other Languages from the University of Wisconsin-River Falls. He has been teaching K-12, University, and adult education classes since 2007 and has worked with students from every continent. Currently, David lives in a small town in the American Upper Midwest. When he’s not teaching or writing, David studies Korean, plays with his son, and takes road trips to Minneapolis to get a taste of city life. Follow David on Google+ and Twitter!