How do you make items in a list or pair grammatically parallel on the ACT, and how do correlative conjunctions and comparisons require matching forms?
Parallel structure on ACT English: matching the grammatical form of items in a series, a pair, or a comparison so each element is the same kind (all nouns, all -ing forms, all clauses), and keeping correlative pairs (not only/but also, either/or) and than/as comparisons parallel.
A focused answer to parallel structure on ACT English: making items in a series, a pair, or a comparison share the same grammatical form, and keeping correlative conjunctions (not only/but also, either/or) and than/as comparisons parallel, with a routine for fixing the odd element in an underlined portion.
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What this skill is asking
Parallel structure means that elements doing the same job in a sentence share the same grammatical form. When you list three activities, they should all be the same kind of word; when you pair two ideas with "not only ... but also", both sides should match; when you compare two things, the compared parts should line up. The ACT plants a single non-matching element and asks you to fix it, so the skill is spotting the odd one out and re-forming it to match.
What parallelism requires
Parallel form is about the type of grammatical unit, not the meaning. If two items are joined or listed, they must be the same kind of structure.
The clue on the ACT is a list or a pair: when you see a series joined by "and" or "or", or a correlative pair, check that every element matches. The wrong element is usually one item switched to a different form (an infinitive among gerunds, a clause among nouns).
Fixing a non-parallel list
The routine is to read the items that are not underlined, identify their shared form, and rewrite the underlined item to match.
Correlative conjunctions and comparisons
Two special structures demand parallelism and show up often.
A frequent comparison trap is comparing unlike things. "The population of Tokyo is larger than Sydney" wrongly compares a population to a city; the parallel version is "larger than that of Sydney" or "larger than Sydney's", comparing population to population.
Why parallelism is a quick win
Parallelism questions reward a simple, repeatable move: find the pattern, match the outlier. They are usually fast, because once you see the list or pair, the established form tells you exactly what the answer must look like, often an infinitive, a gerund, or a noun. The skill overlaps with comparisons (the adjectives-and-comparisons topic) and with verb consistency, so the habit of checking "do these elements match?" pays off across the Conventions category.
Try this
Q1. What must be true of the items in a list joined by "and" on the ACT, and how do you find the right form for a mismatched item? [Recall]
- Cue. The items must share the same grammatical form (all nouns, all -ing gerunds, all infinitives, all clauses). To fix a mismatched item, read the other items, identify their shared form, and rewrite the odd one to match it.
Q2. Explain why "The recipe is easier to follow than memorizing it" is not parallel, and fix it. [Short explanation]
- Cue. The comparison pairs the infinitive "to follow" with the gerund "memorizing", so the two sides do not match in form. Make them parallel: "The recipe is easier to follow than to memorize." Both sides are now infinitives, so the comparison is parallel.
Exam-style practice questions
Practice questions written in the style of ACT exam questions on this dot point, with worked answer explainers. The year tag is the paper they imitate, not the source.
ACT English (style)1 marksChoose the best option: 'On weekends she enjoys hiking, swimming, and to read mystery novels.' (A) NO CHANGE (B) to hike, to swim, and reading (C) reading mystery novels (D) she reads mystery novelsShow worked answer →
The correct answer is (C), "reading mystery novels". The list uses -ing forms ("hiking, swimming"), so the third item must also be an -ing form: "reading". The original breaks the pattern with the infinitive "to read".
Why not the others: (A) keeps the non-parallel "to read"; (B) mixes infinitives and an -ing form, so it is not parallel either; (D) switches to a full clause ("she reads"), which does not match "hiking" and "swimming". Only (C) keeps all three items as -ing forms.
ACT English (style)1 marksChoose the best option: 'The new policy was designed not only to cut costs but also improving service.' (A) NO CHANGE (B) but also to improve service (C) but improving service also (D) but also service improvedShow worked answer →
The correct answer is (B), "but also to improve service". The correlative pair "not only ... but also" must join matching forms. After "not only" comes the infinitive "to cut", so after "but also" the form must also be an infinitive: "to improve".
Why not the others: (A) pairs "to cut" with "improving", which is not parallel; (C) reorders awkwardly and still uses "improving"; (D) switches to a clause ("service improved"). Correlative conjunctions require parallel forms on both sides, so (B) is correct.
Related dot points
- Joining clauses on ACT English: the three connector types (coordinating conjunctions with a comma, subordinating conjunctions that make a clause dependent, and conjunctive adverbs that need a semicolon), how each is punctuated, and choosing the connector whose logical relationship and punctuation are both correct.
A focused answer to joining clauses on ACT English: coordinating conjunctions (comma before, FANBOYS), subordinating conjunctions (make one clause dependent), and conjunctive adverbs (semicolon before, comma after), how each is punctuated, and how to choose the connector whose logic and punctuation are both right.
- Modifier placement on ACT English: the rule that a modifier should sit next to the word it describes, recognizing dangling modifiers (an introductory phrase whose subject is missing) and misplaced modifiers, and fixing an underlined portion so the word right after an introductory modifier is the one it logically describes.
A focused answer to modifier placement on ACT English: the rule that a modifier sits beside what it describes, how dangling modifiers leave an introductory phrase with no logical subject and how misplaced modifiers attach to the wrong word, and how to fix an underlined portion so the modifier lands correctly.
- Verb tense and consistency on ACT English: keeping tense consistent with the surrounding sentences unless the meaning requires a change, using context (other verbs, time words) to set the right tense, and avoiding unjustified shifts in an underlined verb.
A focused answer to verb tense and consistency on ACT English: matching an underlined verb to the tense of the surrounding passage, using time words and nearby verbs to set the tense, and telling a wrong shift from a justified change of time, with a routine for choosing the consistent verb.
- Adjectives, adverbs, and comparisons on ACT English: using adjectives to describe nouns and adverbs to describe verbs, adjectives, and other adverbs (good versus well), and forming comparatives (for two) and superlatives (for three or more) without doubling, such as more taller.
A focused answer to adjectives, adverbs, and comparisons on ACT English: using adjectives for nouns and adverbs for verbs and adjectives (good versus well, real versus really), and forming comparatives for two things and superlatives for three or more without doubling, with a routine for the underlined modifier.
Sources & how we know this
- Description of the ACT English Test — ACT, Inc. (2025)
- Preparing for the ACT Test — ACT, Inc. (2025)