Parallelism in grammar means expressing two or more sentence elements with matching grammatical structures when those elements perform the same function. Parallel words, phrases, or clauses make relationships easier to recognize, while faulty parallelism mixes forms and can obscure meaning, weaken emphasis, or create a grammatical error.
Key facts
Parallel structure matches the grammatical form of coordinated or compared elements.
A list of gerunds should normally contain gerunds, as in reading, writing, and editing.
Correlative conjunctions such as either/or and not only/but also should connect equivalent structures.
Comparisons should compare equivalent forms, such as walking is cheaper than driving.
Parallelism applies to words, phrases, clauses, headings, bullet points, and rhetorical patterns.
Repetition is not always required when English grammar permits controlled ellipsis, but the omitted words must remain recoverable.
What Is Parallelism in Grammar?
Parallelism in grammar is the matching of grammatical structures connected by coordination, comparison, or correlation. The matching elements must perform the same grammatical job, although they do not always need to contain identical words.
For example, The course teaches students to analyze evidence, evaluate sources, and construct arguments uses three infinitive phrases with the same implied subject. The sentence has a predictable structure: to + verb, to + verb, to + verb. Because the second and third instances omit repeated to, the sentence remains parallel.
Faulty parallelism occurs when equivalent elements use different forms:
- Faulty: The program teaches students to analyze evidence, evaluating sources, and argument construction.
- Parallel: The program teaches students to analyze evidence, evaluate sources, and construct arguments.
The correction does more than make the sentence sound smoother. It tells the reader that all three activities occupy the same position in the course description.
Parallelism is therefore a relationship between function, form, and connection. A noun should generally match a noun, a phrase should match a phrase of the same pattern, and a clause should match a clause with a comparable internal structure.
How Does Parallelism Work?
Parallelism works by giving connected elements a shared grammatical template. Coordinating conjunctions, correlative conjunctions, and comparison words signal where the reader should look for that balance.
Consider the template in each example:
| Connection | Faulty structure | Parallel structure | Shared template |
|---|---|---|---|
| Word list | calm, patience, and focused | calm, patient, and focused | adjectives |
| Verb list | drafted, revising, and proofread | drafted, revised, and proofread | past-tense verbs |
| Phrase list | after lunch, before class, and the library | after lunch, before class, and after practice | prepositional phrases |
| Clause list | when the bell rang and students left | when the bell rang and when students left | dependent clauses |
| Comparison | faster than to walk | faster than walking | gerund forms |
The conjunction does not create parallelism by itself. The conjunction exposes a structural relationship that the writer must maintain. In She enjoys hiking and swimming, both gerunds function as objects of enjoys. In She enjoys hiking and to swim, the two objects use different forms.
A practical rule is this: identify the first connected element, name its grammatical form, and test every later element against that form. Then check whether the elements genuinely perform the same function.
What Must Match?
The most important matching features are part of speech, phrase pattern, clause pattern, verb form, and grammatical role. Meaning must also remain comparable.
For example, The manager is responsible for hiring staff and training interns is parallel because hiring staff and training interns are gerund phrases after the preposition for. By contrast, The manager is responsible for hiring staff and to train interns mixes a gerund phrase with an infinitive phrase.
Not every difference is an error. In Maria likes to ski and swimming, the forms are faulty because both items are objects of likes. In Maria wants to ski and enjoys swimming, the forms differ, but the verbs create separate constructions, so parallelism is not required between them.
What Forms Can Be Parallel?
Parallelism can operate at the word, phrase, clause, sentence, and discourse levels. The correct level depends on what the connector joins.
Words and Parts of Speech
Words in a simple series usually match their part of speech and grammatical role.
- Nouns: The workshop requires focus, patience, and creativity.
- Adjectives: The puppy was playful, energetic, and affectionate.
- Adverbs: The machine operates quietly, efficiently, and safely.
- Finite verbs: We planned, tested, and launched the campaign.
A mixed list can be grammatical when the items do not serve the same role. For example, The project was difficult, costly, and a disappointment is sometimes criticized because the first two elements are adjectives and the third is a noun phrase. A clearer revision is The project was difficult, costly, and disappointing.
Phrases
Phrases should normally repeat their syntactic pattern.
| Phrase type | Parallel example | Faulty example | Correction |
|---|---|---|---|
| Gerund phrase | reading reports and checking figures | reading reports and to check figures | reading reports and checking figures |
| Infinitive phrase | to research, to draft, and to revise | to research, drafting, and to revise | to research, to draft, and to revise |
| Prepositional phrase | in the office, at home, or on a train | in the office, home, or on a train | in the office, at home, or on a train |
| Participial phrase | designed for speed and built for durability | designed for speed and durability | designed for speed and built for durability |
Infinitive repetition is often optional after the first item. He plans to study, pass the exam, and graduate early is parallel because the first to establishes the shared infinitive construction. Repeating to can improve emphasis: He plans to study, to pass the exam, and to graduate early.
Clauses
Clauses should match in their subject-verb pattern and level of independence.
- Dependent clauses: The policy requires that employees submit forms and that managers approve them.
- Independent clauses: The team won, the crowd cheered, and the coach celebrated.
- Conditional clauses: If prices fall, if demand rises, and if supply remains stable, the company may expand.
A sentence can contain parallel clauses even when the words differ. The auditor found that records were incomplete and that invoices were missing repeats the complementizer that and gives both findings the same grammatical status.
How Do You Test Parallel Structure?
A six-step editing procedure catches most parallelism errors in under two minutes.
- Circle the connectors. Mark and, but, or, either/or, neither/nor, both/and, not only/but also, than, and as.
- Underline the connected elements. Include the entire phrase or clause, not merely the nearest word.
- Name each form. Label elements as noun, adjective, gerund phrase, infinitive phrase, independent clause, or another structure.
- Check the grammatical job. Confirm that each element is a subject, object, complement, modifier, or comparable clause.
- Rewrite mismatched forms. Choose one pattern and apply it consistently.
- Read the sentence as separate branches. Attach the opening material to each element and verify that every branch remains grammatical.
The splitting test is especially useful:
- Root: The researcher hopes…
- Branch 1: …to collect the data.
- Branch 2: …to compare the results.
- Branch 3: …to publish the findings.
Every branch works. If a branch requires a different preposition, auxiliary, or verb form, the sentence needs revision.
Which Version Is Better?
| Faulty sentence | Parallel revision | Reason |
|---|---|---|
| She likes to swim and running. | She likes swimming and running. | Both objects are gerunds |
| We value honesty, working hard, and accuracy. | We value honesty, hard work, and accuracy. | All objects are nouns |
| The device is compact, reliable, and operates quietly. | The device is compact, reliable, and quiet. | All complements are adjectives |
| He wanted to study, passing, and graduating. | He wanted to study, pass, and graduate. | All verbs use the bare infinitive |
| The role involves planning events and budgets. | The role involves planning events and managing budgets. | Each phrase contains an action |
The best correction preserves the intended meaning before it preserves visual symmetry. Changing working hard to hard work is appropriate only when the writer means the concept of effort rather than the activity of working.
How Should Correlative Conjunctions Work?
Correlative conjunctions should connect equivalent grammatical units as closely as possible. The main pairs are both/and, either/or, neither/nor, not only/but also, and whether/or.
- Both: The proposal is practical and affordable.
- Either: Applicants can submit a portfolio or complete an interview.
- Not only: The update reduced errors but also improved response time.
- Neither: The device is neither cheap nor durable.
Placement matters because the first conjunction should sit immediately before the first item it governs. Compare:
- Less clear: He not only passed the test but also the interview.
- Clearer: He passed not only the test but also the interview.
The first sentence can be interpreted as connecting passed the test with the interview, while the second clearly connects two objects of passed. Some readers accept the first version because the verb can govern both objects, but close placement removes the ambiguity.
Verb agreement requires separate attention with either/or and neither/nor. In formal edited English, the verb generally agrees with the nearer subject:
- Neither the interns nor the supervisor was available.
- Neither the supervisor nor the interns were available.
Writers can avoid awkward agreement by placing the plural subject first: Neither the interns nor the supervisor was available remains grammatically standard, but The supervisor and the interns were unavailable is often more direct.
How Does Parallelism Work in Comparisons?
Parallel comparisons match the forms or meanings of the things being compared. The comparison word may be than, as, like, or more…than, but the compared elements must be logically equivalent.
- Faulty: Driving is faster than to ride a bicycle.
- Parallel: Driving is faster than riding a bicycle.
- Faulty: The salary of a nurse is lower than a teacher.
- Parallel: The salary of a nurse is lower than the salary of a teacher.
- Parallel with ellipsis: A nurse’s salary is lower than a teacher’s.
The second faulty sentence compares a salary with a person. The correction restores the missing noun salary. The final version uses an apostrophe to signal the omitted phrase salary is.
| Comparison type | Faulty | Parallel |
|---|---|---|
| Gerund versus gerund | to walk is easier than running | walking is easier than running |
| Noun versus noun | the cost of tea exceeds coffee | the cost of tea exceeds the cost of coffee |
| Adjective versus adjective | this model is more durable than reliability | this model is more durable than that model |
| Clause versus clause | she works harder than I expected she would | she works harder than I expected |
Parallelism does not require every word to be repeated. English routinely omits predictable material through ellipsis. The omitted material must be grammatically recoverable and must not change the comparison’s meaning.
Where Is Parallelism Used?
Parallel structure improves lists, workplace documents, academic prose, legal drafting, and rhetoric. The form is most visible when readers scan information rather than read every sentence closely.
Bullet Points and Headings
A bullet list should use one consistent grammatical design:
Weak list
- Managing client accounts
- Data analysis
- Prepare monthly reports
- New staff recruitment
Parallel list
- Manage client accounts
- Analyze data
- Prepare monthly reports
- Recruit new staff
The second list uses base-form action verbs. A noun-based version would also work:
- Client-account management
- Data analysis
- Monthly-report preparation
- New-staff recruitment
Do not mix a sentence fragment list with full sentences unless the design intentionally signals different levels of information. A heading such as Benefits of the program can introduce noun phrases, while How to apply can introduce imperative verbs, but each list beneath its heading should remain internally consistent.
Rhetoric and the Rule of Three
Rhetorical parallelism repeats a grammatical or rhythmic structure to strengthen emphasis. Martin Luther King Jr.’s “I Have a Dream” speech uses repeated clause structures, and Abraham Lincoln’s Gettysburg Address uses balanced phrases such as “government of the people, by the people, for the people.”
Rhetorical parallelism is deliberate repetition, not merely error avoidance. A writer may repeat we will across several clauses to create cadence, even when shorter prose would be grammatically sufficient.
Academic and Professional Writing
Parallelism helps readers compare research variables, understand procedures, and scan recommendations. In a methods section, participants completed surveys, attended interviews, and provided consent forms is less precise than participants completed surveys, attended interviews, and provided consent, because the final object changes from an activity to a document.
The construction also supports transparent policy writing: Employees must record hours, report absences, and follow safety procedures. Readers can identify three obligations immediately.
When Is Omission Faulty?
Omission is faulty when removing repeated words leaves a branch incomplete or changes the grammatical relationship. Writers often omit a repeated preposition, auxiliary verb, or particle to make prose concise, but the remaining sentence must still supply the intended structure.
- Faulty: London is a city I have visited and want to return.
- Parallel: London is a city I have visited and want to return to.
- Clearer: London is a city that I have visited and to which I want to return.
The verb return requires to in the intended meaning. The preposition cannot be borrowed from visited.
Another example involves auxiliary verbs:
- Ambiguous: The report was accurate and submitted on time.
- Parallel: The report was accurate and was submitted on time.
The shorter version is grammatical because was can function as the linking verb for accurate and the auxiliary for submitted. Repeating the auxiliary improves clarity when the sentence is long or the two predicates might be misread.
A useful practitioner rule is to restore every omitted word mentally. If the full version is grammatical and the omission leaves the meaning unchanged, ellipsis is probably acceptable. If the restored branches require different prepositions or subjects, revise the sentence.
Common Faulty Parallelism Errors
| Error pattern | Example | Reliable fix |
|---|---|---|
| Gerund and infinitive mix | likes cooking and to bake | likes cooking and baking |
| Noun and adjective mix | a person of honesty and honest | a person who is honest and dependable |
| Unequal verb forms | planned, researching, and writes | planned, researched, and wrote |
| Correlative mismatch | either driving or to take a train | either driving or taking a train |
| Comparison mismatch | more useful than cost | more useful than the cost |
| Omitted required preposition | visited and returned | visited and returned to |
Parallelism errors often occur because writers edit only the nearest words. The real unit may be much larger: to improve customer retention must be compared with to reduce service delays, not merely with reduce.
A second expert rule is to compare grammatical roles before surface endings. Two words ending in -ing are not automatically parallel if one is a gerund and the other is a participle modifying a noun.
A third rule concerns semantic comparability. The analyst values accuracy, speed, and the software has three noun phrases, but the third item is not the same kind of thing as the first two. Grammatical matching alone cannot repair a category error.
Is Faulty Parallelism Always a Serious Error?
Faulty parallelism is serious when it obscures coordination, creates an unintended comparison, or breaks a required construction. Minor stylistic imbalance can be acceptable when the meaning is immediate and the sentence benefits from natural variation.
Formal writing, examinations, contracts, résumés, and instructions require stricter control because readers need rapid, unambiguous comparisons. Creative writing may break parallelism intentionally to represent interruption, contrast, or a change in perspective.
Standardized tests such as the SAT, ACT, and GMAT commonly test parallel structure, but unsupported claims that parallelism forms a fixed percentage of all sentence-correction questions should be treated cautiously. Test content varies by exam, edition, and question pool; official test specifications are more reliable than universal percentages found in study summaries.
Parallelism is also not a requirement to repeat every article, preposition, or auxiliary. Overcorrection can make prose mechanical: She likes to read, to write, and to edit is correct, while She likes reading, writing, and editing is equally correct and often more concise.
How Can You Practice Parallelism?
Use short transformations that isolate one structural choice at a time.
- Convert every item in a list to nouns.
- Convert every item to gerund phrases.
- Convert every item to infinitive phrases.
- Expand omitted words in a comparison.
- Split a sentence into independent branches.
- Read a bullet list without its introductory heading.
Practice set:
- The role requires accuracy, working quickly, and communication.
Revision: The role requires accuracy, speed, and communication. - The committee will review the proposal, consulting experts, and issue a decision.
Revision: The committee will review the proposal, consult experts, and issue a decision. - The course is designed to teach research methods and critical thinking.
Revision: The course is designed to teach research methods and develop critical thinking.
This revision makes the actions parallel, although the original may be acceptable because teach can govern both objects. - The service is faster than the older system is reliable.
Revision: The service is faster than the older system.
Or: The service is faster than the older system is.
The correct revision depends on the intended comparison. Parallelism editing is not a mechanical exercise in copying endings; it is an analysis of what the writer means to connect.
FAQ About Parallelism in Grammar
What Is a Simple Example of Parallelism?
A simple example is She likes reading, writing, and editing. The three gerunds function as objects of likes and have the same -ing form. The faulty version, She likes reading, writing, and to edit, mixes gerunds with an infinitive.
What Are the Three Rules of Parallelism?
Three practical rules cover most cases: match the grammatical form of connected elements, place correlative conjunctions before equivalent structures, and compare equivalent things or phrases. Writers should also check omitted prepositions and auxiliary verbs because ellipsis can conceal a mismatch.
What Is the Difference Between Parallelism and Repetition?
Parallelism matches grammatical structure, while repetition repeats words, sounds, or ideas. She planned, drafted, and revised uses parallel verbs without repeating the subject. We will plan, we will draft, and we will revise uses both parallelism and deliberate rhetorical repetition.
Can Parallelism Use Different Words?
Yes. Parallelism requires matching structure and function, not identical vocabulary. The team analyzed evidence, debated alternatives, and reached a decision uses different verbs, but all three are coordinated past-tense predicates with the same subject.
Is “Not Only” Always Followed by “But Also”?
In formal parallel prose, not only is normally paired with but also, but the second phrase may be omitted when the construction is obvious. Writers should retain both parts when the sentence is complex, because the pair makes the relationship and emphasis easier to follow.
How Do You Find Parallelism on a Grammar Test?
Locate conjunctions and comparison words, underline the elements they connect, and label each element’s form. Check for gerund-infinitive mixtures, unequal clauses, misplaced correlative pairs, and comparisons between unlike things. Then choose the answer that preserves meaning with the clearest shared structure.
The Bottom Line
Parallelism in grammar matches the forms of words, phrases, or clauses that perform the same function. Find the connector, isolate the complete elements, identify their grammatical pattern, and test each branch separately. Use parallel structure for clarity, but allow controlled ellipsis and intentional rhetorical variation when the meaning remains precise.
