Parallel Structure: Matching Form to Form

Parallel structure is the grammar of balance. When you string ideas together — in a list, a comparison, or a paired construction — each piece should take the same grammatical shape. "She likes hiking, biking, and to swim" jars the ear because the last item breaks the -ing pattern. Fix it to "swimming" and the sentence clicks into place. The tests are built to catch exactly these breaks.

This guide shows parallelism in lists, comparisons, and correlative pairs, with worked and practice examples matched to real test difficulty at Northside Tutoring.

Why Parallelism Matters

Parallel-structure questions appear regularly on the SAT Writing module and ACT English. They reward a simple habit: when you see a list or comparison, check that every element matches in form. Beyond tests, parallelism is a hallmark of polished, persuasive writing.

What Parallel Structure Is

Parallelism means using the same grammatical form for ideas that play the same role. If one item is a verb in -ing form, they all should be. If one is a noun phrase, they all should be. The pattern, once started, must continue.

Parallelism in Lists

Every item in a list must share a form:

Faulty	Parallel
to read, to write, and speaking	to read, to write, and to speak
brave, loyal, and a hard worker	brave, loyal, and hardworking

Parallelism in Comparisons

When you compare two things, both sides of the comparison must match in form. "I would rather walk than to drive" is faulty; make it "rather walk than drive." Comparisons with "than" and "as" are common test targets.

Correlative Pairs

Correlative conjunctions come in pairs and demand parallel structure on each side:

• not only…but also
• either…or / neither…nor
• both…and

How to Spot and Fix It

When you see a list, comparison, or correlative pair, line the items up and check their forms. The error is almost always a single item that doesn't match; the fix is to rewrite that item into the shared form. Reading the items as a vertical list in your head makes the odd one out jump out.

Where You'll See This — Test by Test

Parallelism is fixed grammar, tested the same everywhere. The SAT Writing module and ACT English test it in lists, comparisons, and correlative constructions; the SSAT checks it in sentence correction.

Watch the Lesson

Sometimes a diagram needs a voice. In the short video below, one of our Northside tutors walks through the core idea and works through test-style problems in real time.

Worked Example Problems

These problems are calibrated to the difficulty you'll actually see on test day. Try each one before opening the solution.

Common Mistakes to Avoid

Practice Problems — You Try

Three problems below. Work each before checking the solution.

The Northside Method — How We Teach This 1-on-1

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