SAT Parallelism: Match Grammatical Form in Lists and Comparisons

Parallelism means expressing items that play the same grammatical role in the same grammatical form.

Incorrect:

The internship required collecting samples, analyzing data, and to write reports.

The first two items are gerunds:

• collecting;
• analyzing.

The third switches to an infinitive:

• to write.

Better:

The internship required collecting samples, analyzing data, and writing reports.

The SAT often hides a parallelism error inside a long sentence. The fastest method is to identify the words being coordinated and compare their forms.

Why parallelism belongs to Standard English Conventions

College Board's Standard English Conventions domain includes Form, Structure, and Sense.

Parallelism is a structure question because elements joined by:

• and;
• or;
• but;
• either...or;
• neither...nor;
• not only...but also;

should line up grammatically when they perform equivalent functions.

The issue is not simply "make things sound balanced." It is structural equivalence.

Lists should match

Correct:

The study required planning, testing, and reporting.

All gerunds.

Also correct:

The team planned to collect samples, to analyze them, and to publish the results.

All infinitive phrases.

The forms do not have to be one-word items. They have to be grammatically parallel.

Worked example 1: list mismatch

The new role involves writing reports, presenting findings, and ___.

Choices:

A. to supervise interns
B. supervising interns
C. interns are supervised
D. the supervision of interns occurred

The existing list uses gerunds:

• writing;
• presenting.

So the parallel choice is:

supervising interns

Parallelism after a shared introductory word

Sometimes a preposition or verb is shared across list items.

The researcher is responsible for collecting samples, recording measurements, and maintaining equipment.

"for" applies to all three gerund phrases.

You do not need to repeat it unless the structure calls for repetition.

Infinitives: repeat or share consistently

Both can be grammatical:

The program aims to reduce costs, improve access, and increase efficiency.

The first "to" can govern all three verbs.

Also possible:

The program aims to reduce costs, to improve access, and to increase efficiency.

What matters is consistent structure.

Worked example 2: shared infinitive

The committee hopes to expand the archive, digitize rare documents, and ___ public access.

Parallel verbs after one shared "to":

improve

not "improving" or "to improving."

Correlative conjunctions

Paired structures include:

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

The grammatical form after each half should match.

Incorrect:

The device is useful not only for measuring temperature but also to track humidity.

Better:

...not only for measuring temperature but also for tracking humidity.

Or:

...not only to measure temperature but also to track humidity.

Worked example 3: not only / but also

The study sought not only to identify the pattern but also ___ its cause.

Parallel to:

to identify

Best:

to explain

Either/or structure

Incorrect:

The researcher will either revise the paper or the experiment will be repeated.

The two sides are different structures.

Better:

The researcher will either revise the paper or repeat the experiment.

Same subject and verb form.

Comparison parallelism

Compare like grammatical and logical entities.

Incorrect:

The novels of Author A are longer than Author B.

This compares:

• novels;
• a person.

Better:

The novels of Author A are longer than those of Author B.

Or:

Author A's novels are longer than Author B's.

Parallelism and logical comparison overlap.

Worked example 4: comparison

The climate of City A is warmer than ___.

Best if comparing climates:

that of City B

not "City B."

"That" stands for "the climate."

"Than" and "as" comparisons

Make the compared items structurally clear.

The new method is more efficient than the old method.

Correct.

The new method is more efficient than using the old method.

This compares a method with an activity phrase—potentially mismatched.

A better rewrite may be:

Using the new method is more efficient than using the old method.

Parallel clauses

Parallelism can occur at clause level:

The researchers found that the signal was weak and that the background noise was high.

You may sometimes omit the repeated "that":

...found that the signal was weak and the background noise was high.

But if omission creates ambiguity, repeated structure can improve clarity.

Worked example 5: clause-level balance

The report concluded that the treatment reduced symptoms and ___.

If second result is another clause about treatment:

that it improved sleep quality

can produce especially clear parallel structure.

Verb tense can interact with parallelism

Incorrect:

The scientist collected the samples, analyzed the data, and will publish the findings.

This may be logically correct if publication is future, but it is not parallel in time.

If all actions occurred:

collected, analyzed, and published.

If timeline truly differs, the sentence should clearly signal that difference rather than forcing artificial parallelism.

See SAT Verb Tense and Form.

Parallelism does not mean identical words

Correct:

The lecture was informative, engaging, and brief.

All adjectives.

Correct:

The lecture explained the theory, illustrated its applications, and addressed common objections.

All verb phrases.

The content can differ; grammatical roles should match.

Worked example 6: adjective series

The material is lightweight, durable, and ___.

Best parallel choice:

flexible

not "it can be recycled" if all three are intended as coordinate adjectives.

Parallelism with prepositions

Incorrect:

The policy applies to students, faculty members, and on-campus contractors.

Actually this list can be parallel because "to" governs all noun phrases:

to students, faculty members, and on-campus contractors.

But if the sentence were:

The policy applies to students, for faculty, and among contractors,

the prepositional relationships would not match.

Parallelism and punctuation

Commas separate list elements, but punctuation cannot repair unequal grammar.

A perfectly punctuated list can still be nonparallel.

That is why you should solve structure before punctuation.

See SAT Comma Rules.

Parallelism can involve whole phrases, not just one word

A common mistake is to compare only the first word in each list item.

Consider:

The program was designed to reduce processing time, to improve record accuracy, and to make archived files easier to search.

Each item is an infinitive phrase, even though the phrases have different lengths.

Now compare:

The program was designed to reduce processing time, improving record accuracy, and to make archived files easier to search.

The middle item changes grammatical form.

The important comparison is:

• to reduce;
• improving;
• to make.

That mismatch is the error.

Worked example 7: long parallel phrases

The expedition's goals were to map the northern coast, to collect sediment samples from offshore sites, and ___.

The first two goals begin with to + base verb.

A parallel completion would be:

to document changes in shoreline vegetation

The length of the phrase does not matter. Its grammatical role does.

Parallelism inside comparisons with "than" and "as"

Comparison questions can hide a second issue: logical equivalence.

Consider:

The salary of engineers in Region A is higher than Region B.

The sentence compares:

• a salary;
• a region.

That is illogical.

Better:

The salary of engineers in Region A is higher than that of engineers in Region B.

The pronoun that stands for the salary.

Another clean version:

Engineers in Region A earn higher salaries than engineers in Region B.

The SAT can test this kind of comparison even when every individual word is grammatical.

Worked example 8: compare equivalent things

The wingspan of Species X is greater than ___.

If the comparison is with the wingspan of Species Y:

that of Species Y

Do not choose simply Species Y, because that compares a measurement with an animal.

Parallelism with "both...and"

Both should introduce the first of two genuinely parallel elements.

Correct:

The policy will both reduce delays and lower costs.

The paired verbs are:

• reduce;
• lower.

Also correct:

The policy will benefit both small businesses and nonprofit organizations.

The paired noun phrases are:

• small businesses;
• nonprofit organizations.

Awkward:

The policy both will reduce delays and costs will fall.

The structures after the two sides no longer match.

Placement matters

Compare:

The scientist both collected and analyzed the samples.

with:

The scientist collected both soil and water samples.

The position of both tells the reader which elements are being paired.

On a difficult SAT item, locate the paired conjunction before judging the answer choices.

"Not only...but also" can test meaning as well as form

Parallel structure is necessary, but it is not the only requirement.

The device not only records temperature but also measures humidity.

Grammatically parallel:

• records;
• measures.

But if an answer choice produces:

not only records temperature but also humidity is measured,

the second half shifts to a different clause structure.

Another subtle issue is scope.

The researcher not only interviewed teachers but also surveyed students.

The paired elements are two actions.

If the word placement changes:

The researcher interviewed not only teachers but also students.

Now the paired elements are two groups of people.

Both sentences may be grammatical, but they emphasize different relationships.

Parallelism in headings, descriptions, and definitions

The SAT often uses academic prose where a sentence defines several characteristics.

Example:

The technique is valued for its accuracy, its speed, and its ability to work with small samples.

The three items are noun phrases:

• its accuracy;
• its speed;
• its ability...

A tempting alternative might be:

its accuracy, operating quickly, and its ability...

The meaning is understandable, but the structure is not parallel.

Worked example 9: noun-phrase series

The ecosystem is notable for its biodiversity, its resistance to seasonal drought, and ___.

Best:

its unusually rapid recovery after fires

All three items are noun phrases beginning with its.

Parallelism can reveal the missing part of a sentence

Sometimes you do not need to understand every technical term.

Example:

The compound can be extracted from leaves, synthesized in a laboratory, or ___ from recycled material.

The pattern is:

• can be extracted;
• [can be] synthesized;
• [can be] ___.

The missing choice should be a past participle compatible with the shared auxiliary can be.

For example:

recovered

Pattern recognition can reduce the amount of content knowledge you need.

Do not force parallelism when the ideas have different grammatical jobs

Not every nearby phrase must look the same.

Consider:

Because the road was flooded, the organizers canceled the event.

• Because the road was flooded is a dependent clause giving a reason.
• the organizers canceled the event is the independent clause.

These parts do different jobs, so they do not need parallel form.

Parallelism matters when elements occupy equivalent roles:

• items in a list;
• paired alternatives;
• coordinated predicates;
• compared entities;
• paired clauses.

The question is not “Do these phrases look alike?”

It is:

Are these phrases doing the same job?

A deeper method: identify the sentence frame

On harder questions, strip away details and expose the frame.

Original:

The new conservation program aims not only to restore wetlands damaged by development but also to creating long-term habitat corridors for migratory species.

Frame:

aims not only to restore but also to creating

Now the error is obvious.

Correct:

aims not only to restore but also to create

This compression technique is especially useful when scientific names, dates, or descriptive phrases make the sentence look more complicated than its grammar really is.

Worked example 10: compress the frame

The historian sought both to identify the manuscript's original owner and determining when later annotations were added.

Compress:

sought both to identify and determining

Mismatch.

Best correction:

to determine

Now:

sought both to identify and to determine

The structure matches.

Parallelism vs agreement vs tense

These grammar skills can overlap, so solve them in the right order.

Example:

The researchers collected the samples, analyzed the results, and publishes their conclusions.

There are two clues:

• list parallelism suggests three coordinated past-tense verbs;
• tense consistency supports the same conclusion.

Correct:

collected, analyzed, and published.

Now:

The researcher collects samples, analyzes results, and publishes conclusions.

Here all three verbs are present tense and agree with the singular subject.

The answer is not “always make verbs past.” The answer is “make equivalent actions fit the intended timeline and subject.”

Use SAT Verb Tense and Form when time is the deciding issue and SAT Subject-Verb Agreement when number is the issue.

Parallelism in paired prepositions

A sentence may pair complete prepositional phrases:

The artifacts were found beneath the floor and inside the eastern wall.

Both are prepositional phrases.

Or it may share one preposition:

The artifacts were found in storage rooms, burial chambers, and courtyards.

Both structures can be correct.

The trap is an unjustified shift:

The artifacts were found in storage rooms, burial chambers, and within courtyards.

This may be understandable, but if the choices offer a cleaner parallel construction, the SAT will favor the form that clearly coordinates equivalent elements.

Advanced practice: diagnose the exact mismatch

Example A

The course teaches students to evaluate sources, constructing arguments, and to revise drafts.

Forms:

• to evaluate;
• constructing;
• to revise.

Error: middle item.

Best correction:

to construct arguments

Example B

The new telescope is more sensitive than the previous observatory.

Compared:

• telescope;
• observatory.

This may be a logical mismatch if the intended comparison is sensitivity of instruments.

A clearer version could be:

The new telescope is more sensitive than the previous telescope.

Example C

The organization supports both preserving historic buildings and the creation of new public spaces.

Paired forms:

• preserving...;
• the creation...

Better:

supports both preserving historic buildings and creating new public spaces.

or:

supports both the preservation of historic buildings and the creation of new public spaces.

Two different rewrites can be grammatical. The SAT answer choices determine which clean parallel frame is available.

Common traps

Trap 1: match meaning but not grammar

Items can be conceptually related yet structurally mismatched.

Trap 2: gerund mixed with infinitive

"collecting, analyzing, and to report."

Trap 3: noun compared with person

Compare like with like.

Trap 4: correlative conjunction halves misaligned

Check what follows both parts.

Trap 5: repeat too much or too little

Shared words can govern multiple items, but the underlying form must remain clear.

Trap 6: punctuation distracts from structure

Ignore commas first and inspect item forms.

A 20-second SAT parallelism routine

1. Find coordinating word:
   • and/or/but;
   • either/or;
   • not only/but also.
2. Identify the elements it joins.
3. Label each form:
   • noun;
   • gerund;
   • infinitive;
   • adjective;
   • clause.
4. Make equivalent roles match.
5. For comparisons, ensure like is compared with like.
6. Then check tense and punctuation.

SAT-style practice

Question 1

The internship involves researching sources, interviewing experts, and ___.

drafting reports

Question 2

The policy aims to reduce waste, lower costs, and ___ efficiency.

increase

Question 3

The device is useful both for measuring pressure and ___ temperature.

for monitoring

Question 4

The paintings of Artist A are larger than ___.

those of Artist B

Question 5

The scientist not only collected samples but also ___ them.

analyzed

FAQ: SAT parallelism

What is parallel structure?

Using matching grammatical forms for elements that perform equivalent roles.

Do all items in a list need the same part of speech?

They should have structurally parallel forms appropriate to their roles.

What should I check with "not only...but also"?

The structures following both halves should match.

How do comparisons create parallelism errors?

The sentence may compare unlike things, such as a person's work with another person.

Can one "to" apply to several infinitives?

Yes: "to collect, analyze, and report."

Is parallelism only about lists?

No. It also appears in comparisons, paired conjunctions, and clauses.

How to practice this on MastaPrep

Reading a guide shows you the method. Making it automatic takes spaced, targeted practice. MastaPrep's placement check finds the SAT Reading and Writing skills that cost you the most, your study plan schedules short sets on them, and every answer comes with a worked explanation. Questions you miss return for review later, so a mistake you have fixed stays fixed.

See how MastaPrep works or start with free SAT practice questions. No credit card is needed for the free plan.

Related MastaPrep guides

• SAT Subject-Verb Agreement
• SAT Modifiers
• SAT Pronouns and Possessives
• SAT Verb Tense and Form
• SAT Comma Rules

Final takeaway

When two or more elements do the same grammatical job, make their forms line up:

noun with noun, gerund with gerund, infinitive with infinitive, clause with clause

On the SAT, the fastest move is to find the conjunction and compare the structures directly.

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Official SAT references:
https://satsuite.collegeboard.org/sat/whats-on-the-test/reading-writing
https://satsuite.collegeboard.org/practice/student-question-bank/reading-writing

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