Parallel structure means expressing ideas of equal importance in the same grammatical form. A sentence sounds clearer and more polished when items in a list or comparison consistently use nouns, verbs, infinitives, or clauses.
How to fix parallel structure
First, identify the words or phrases being connected by and, or, but, either/or, neither/nor, or not only/but also. Then make sure each connected element follows the same pattern.
Gerunds: use “-ing” forms consistently
Not parallel:
She enjoys hiking, swimming, and to ride a bicycle.
Parallel:
She enjoys hiking, swimming, and riding a bicycle.
All three activities now use the -ing form.
Infinitives: use “to” consistently
Not parallel:
The program helps students to improve their writing, develop confidence, and communicating effectively.
Parallel:
The program helps students improve their writing, develop confidence, and communicate effectively.
Alternatively:
The program helps students to improve their writing, to develop confidence, and to communicate effectively.
Either version works because the grammatical pattern remains consistent.
Nouns: keep list items in noun form
Not parallel:
The position requires patience, accuracy, and being dependable.
Parallel:
The position requires patience, accuracy, and dependability.
Clauses: repeat the same clause structure
Not parallel:
The manager said that the deadline was firm and everyone must submit the report by Friday.
Parallel:
The manager said that the deadline was firm and that everyone must submit the report by Friday.
Comparisons: compare equivalent things
Not parallel:
Working from home is more convenient than when you commute to an office.
Parallel:
Working from home is more convenient than commuting to an office.
The revision compares one activity with another activity.
Correlative conjunctions: place paired words correctly
With expressions such as not only/but also and either/or, the words following each part should match.
Not parallel:
The course not only teaches students to analyze evidence but also persuasive writing.
Parallel:
The course teaches students not only to analyze evidence but also to write persuasively.
Quick editing method
- Underline each item being joined or compared.
- Label its grammatical form: noun, gerund, infinitive, phrase, or clause.
- Choose the form that communicates the meaning most naturally.
- Rewrite every item in that same form.
- Read the sentence aloud to check its rhythm.
A reusable prompt for correcting a specific sentence is:
Correct the parallel structure in the sentence below. Preserve its original meaning, explain what was inconsistent, and provide one polished revision:
“[Insert sentence]”
The key test is simple: connected ideas should sound as though they belong to the same grammatical family.