Parallel Structure in English: Keep Your Sentences Balanced

Published: 2026-05-15 · 6 min read

Parallel structure — also called parallelism or parallel construction — means using the same grammatical form for related elements in a sentence. When you list items, make comparisons, or pair ideas with conjunctions, matching their grammatical forms makes your writing clearer, more rhythmic, and more professional.

Broken parallelism is one of the most common errors in English writing. The fix is usually simple: make sure every item in a series or pair uses the same grammatical pattern.

What Is Parallel Structure?

Parallel structure means that words, phrases, or clauses in a series or pair share the same grammatical form. Nouns pair with nouns. Infinitives pair with infinitives. Gerunds pair with gerunds. Clauses pair with clauses.

Not parallel (wrong): She likes hiking, to swim, and running.
Parallel (correct): She likes hiking, swimming, and running.

In the first version, "hiking" and "running" are gerunds, but "to swim" is an infinitive. The mismatch feels awkward. The second version uses three gerunds, and the sentence flows smoothly.

Why does this matter? Readers subconsciously expect consistency. When the pattern breaks, even for a moment, it disrupts comprehension. Professional writing maintains parallel structure without exception.

Parallel Structure in Lists and Series

This is where parallelism errors appear most frequently. When you list three or more items, every item must follow the same grammatical pattern.

Lists of Nouns

Not parallel: The package includes a manual, software, and how to get support.
Parallel: The package includes a manual, software, and a support guide.

Lists of Verbs

Not parallel: Our goals are to expand market share, increase revenue, and satisfying customers.
Parallel: Our goals are to expand market share, increase revenue, and satisfy customers.

Not parallel: The manager asked the team to review the report, update the timeline, and that they should communicate with stakeholders.
Parallel: The manager asked the team to review the report, update the timeline, and communicate with stakeholders.

Lists of Adjectives

Not parallel: The candidate is intelligent, ambitious, and has experience.
Parallel: The candidate is intelligent, ambitious, and experienced.

Lists of Phrases

Not parallel: We searched in the database, through the files, and checked the logs.
Parallel: We searched through the database, through the files, and through the logs.

Parallel Structure with Correlative Conjunctions

Correlative conjunctions always come in pairs: both/and, either/or, neither/nor, not only/but also, whether/or. The structure following the first half must match the structure following the second half.

Both / And

Not parallel: The proposal was both innovative and it was practical.
Parallel: The proposal was both innovative and practical.

Either / Or

Not parallel: You can either pay online or you can mail a check.
Parallel: You can either pay online or mail a check.

Not Only / But Also

Not parallel: The software not only tracks expenses but also for generating reports.
Parallel: The software not only tracks expenses but also generates reports.

Neither / Nor

Not parallel: The device is neither easy to use nor is it affordable.
Parallel: The device is neither easy to use nor affordable.

Parallel Structure in Comparisons

When you compare two things using "than" or "as," the items being compared should have parallel grammatical forms.

Not parallel: Writing a novel is harder than to write a short story.
Parallel: Writing a novel is harder than writing a short story.

Not parallel: I find cooking more relaxing than to clean the house.
Parallel: I find cooking more relaxing than cleaning the house.

Not parallel: It's as important to listen as speaking.
Parallel: It's as important to listen as to speak.

Parallel Structure with Headings and Bullet Points

Parallelism applies to document design too. All headings at the same level should use the same grammatical form. All bullet points in a list should start with the same part of speech.

Not parallel (mixed verb forms):

Parallel (all gerunds):

Parallel (all imperative verbs):

This principle applies to resume bullet points, presentation slides, website navigation menus, and table of contents entries. Consistency at every level signals attention to detail.

Subtle Parallelism Errors

Some parallelism errors are harder to spot because the sentence sounds almost right. Watch for these patterns:

Mixing active and passive voice:
Not parallel: The team designed the product and the marketing plan was created by them.
Parallel: The team designed the product and created the marketing plan.

Mixing full clauses with phrases:
Not parallel: I admire her persistence and that she never gives up.
Parallel: I admire her persistence and determination.

Missing words in repeated structures:
Not parallel: The data was collected from January to March and from April to June and July.
Parallel: The data was collected from January to March, from April to June, and from July to September.

Why Parallelism Matters

Clarity. Parallel structure removes ambiguity. When grammatical forms match, relationships between ideas are immediately clear. The reader doesn't have to backtrack and reread.

Rhythm. Parallel constructions create a natural cadence. This is especially important in speeches, presentations, and persuasive writing — think of Martin Luther King's "I have a dream" refrains or Churchill's "We shall fight on the beaches" speech.

Professionalism. Parallelism errors are one of the first things editors notice. A document with broken parallelism feels sloppy, even if the reader can't articulate exactly why. Getting this right elevates your writing from amateur to polished.

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