Parallel Structure: Rules, Examples and Common Errors

Writing a sentence with three items in a list feels simple until one of them quietly breaks the pattern. That small inconsistency, mixing a noun with a verb form or an infinitive with a gerund, is called faulty parallelism, and it is one of the errors that most reliably signals a lack of grammatical control to examiners and readers alike. Understanding parallel structure helps you write sentences that are grammatically correct, clear, and persuasive.

What Is Parallel Structure?

Parallel structure (also called parallelism) is the principle that grammatically linked items must share the same grammatical form. Items joined by coordinating conjunctions (and, but, or), correlative conjunctions (both...and, not only...but also), or comparative phrases (than, as...as) all fall under this rule.

A simple test: strip each item down and check whether it could stand in the same grammatical slot. If it can, the structure is parallel. If it cannot, revise until it can.

Word order shapes clarity too. You can read more in this guide to English sentence structure.

Why Parallelism Matters in Exam Writing and CVs

Examiners assessing writing at B2 level and above use descriptors that explicitly reward "a variety of structures used with flexibility and accuracy." Faulty parallelism is the opposite: it shows that a complex structure was attempted but not controlled.

CV bullet points follow the same logic. Every bullet in a "Key Achievements" or "Responsibilities" section should open with the same word class, typically an action verb in the past simple. Mixing "Managed a team of six" with "Responsible for quarterly reports" in the same section reads as inconsistent and reduces the document's professional impact.

Before applying these rules in a formal exam context, it helps to know which level you are working at. An overview of all English levels can help you place your current grammar skills on the CEFR scale.

Parallel Structure in Lists

The most common context for parallelism is a simple list of three or more items joined by "and" or "or."

The rule: every item must be the same part of speech or verb form.

Fixing the error means picking a form, gerund, infinitive, or adjective, and applying it to every item in the list without exception.

Lists with Verbs

When listing actions, choose one verb form and keep it throughout.

• Faulty: The manager decided to reorganise the team, cutting costs, and that new targets would be set.
• Parallel: The manager decided to reorganise the team, to cut costs, and to set new targets.

All three items now use the infinitive form, so the sentence is balanced.

Lists in CV Bullet Points

• Faulty: Coordinated weekly meetings. Responsible for budget tracking. Gave client presentations.
• Parallel: Coordinated weekly meetings. Tracked the monthly budget. Delivered client presentations.

All three now open with a past simple action verb.

Parallel Structure with Correlative Conjunctions

Correlative conjunctions are paired linking words that must connect grammatically identical structures. The most important pairs to know are:

• both...and
• not only...but also
• either...or
• neither...nor
• whether...or

The rule: whatever grammatical form follows the first conjunction must also follow the second.

A reliable technique: say the sentence aloud, placing the two halves side by side. If they sound mismatched, they are mismatched grammatically.

Parallel Structure in Comparisons

Comparisons using "than" or "as...as" must connect like with like. Comparing a noun to a clause, or a gerund to an infinitive, produces faulty parallelism.

In comparisons, identify the first element, noun, gerund, infinitive, or clause, and make the second element its grammatical mirror.

How Examiners Identify Parallelism Errors

Writing tests at B2 and C1 level assess grammatical range and accuracy as separate criteria. Parallelism errors affect both. A sentence with a faulty list shows range (a complex structure was attempted) but penalises accuracy (it was not executed correctly). The net effect is a mid-range mark rather than a high one.

Catching parallelism errors before they reach an examiner takes practice on real writing tasks, where feedback can show you the specific patterns you repeat. A focused English writing test gives you the opportunity to produce extended writing and receive structured feedback on grammatical patterns, including parallelism.

For a broader look at developing the full range of writing skills, the article on how to improve English writing skills covers planning, coherence, and grammatical accuracy together.

Practice Exercise: Correct These Eight Sentences

Read each sentence and rewrite it so that the structure is parallel. The answers appear below.

1. The report should be clear, concise, and it must have accuracy.
2. She enjoys reading novels, to cook new recipes, and taking long walks.
3. The job requires either relevant experience or you must have a recognised qualification.
4. Learning to budget is more useful than when you borrow money without a plan.
5. He not only passed the exam but also his interview was successful.
6. Our goals are to increase revenue, reducing overheads, and customer satisfaction.
7. The trainer asked us to listen carefully, taking notes, and ask questions.
8. Both the design team and the work done by the developers was praised.

Suggested Answers

1. The report should be clear, concise, and accurate.
2. She enjoys reading novels, cooking new recipes, and taking long walks.
3. The job requires either relevant experience or a recognised qualification.
4. Learning to budget is more useful than borrowing money without a plan.
5. He not only passed the exam but also succeeded in the interview.
6. Our goals are to increase revenue, reduce overheads, and improve customer satisfaction.
7. The trainer asked us to listen carefully, take notes, and ask questions.
8. Both the design team and the development team were praised.

Conclusion

Parallel structure is one of the most teachable and most testable aspects of advanced English grammar. Keep these points in mind:

• Every item in a list must use the same grammatical form: noun, verb, gerund, or infinitive.
• Correlative conjunctions (both...and, not only...but also, either...or) demand matching structures on both sides.
• Comparisons with "than" or "as...as" must connect like with like.
• CV bullet points should all open with the same word class, usually an action verb.
• Examiners at B2 and above penalise faulty parallelism under both grammatical range and accuracy descriptors.
• Reading your sentences aloud, item by item, is the fastest way to catch a mismatch before you submit.

Ready to see how your writing holds up under exam conditions? Take the English writing test and get feedback on grammatical accuracy, including parallelism, in your own writing.