Parallel Structure on the SAT: Matching Form in Lists and Comparisons

Parallel structure (or parallelism) means that items in a list, series, or comparison have the same grammatical form. In the sentence "The student likes reading, writing, and to compute mathematics," the first two items ("reading," "writing") are gerunds (verb forms ending in -ing), but the third ("to compute") is an infinitive. This inconsistency breaks parallelism. A corrected version: "The student likes reading, writing, and computing" (all gerunds). Parallel structure improves readability and emphasizes that items are of equal importance. Faulty parallelism can make a sentence sound awkward and confusing. When you see a list or series, check that all items have the same grammatical form: all nouns, all verbs, all adjectives, or all clauses, depending on the context. Lists in parallel structure often appear with coordinating conjunctions (and, but, or) or in items separated by commas.

Parallel structure applies to many grammatical contexts. In lists: "She enjoys hiking, swimming, and biking" (all gerunds). In pairs compared with "both...and": "She both loves singing and dancing" (infinitives). In comparisons with "either...or": "Either study hard or fail the test" (verb phrases). In series with correlative conjunctions: "The proposal is neither practical nor affordable" (adjectives). Recognizing the context helps you identify what form is expected and spot where the parallelism breaks down. On the SAT, parallel structure questions present sentences where items in a series or comparison fail to match grammatically, and you are asked to correct the error.

Mixing different types of words in a list breaks parallelism. "The car is fast, reliable, and costs little" mixes adjectives (fast, reliable) with a verb phrase (costs little). Corrected: "The car is fast, reliable, and inexpensive" (all adjectives). "The responsibilities include supervising staff, managing budgets, and to report to senior management" mixes gerunds (supervising, managing) with an infinitive (to report). Corrected: "The responsibilities include supervising staff, managing budgets, and reporting to senior management" (all gerunds). Mixed grammatical forms are easy to miss when reading quickly, so slow down on sentences with lists and check that each item has the same form. Correlative conjunctions (both/and, either/or, neither/nor, not only/but also) require special attention because they link paired items that must be parallel. "Not only did she study hard but also she practiced extensively" is awkward because the structures are different. Better: "She not only studied hard but also practiced extensively" (parallel verb phrases).

Faulty parallelism can be subtle. "The ingredients needed are flour, sugar, and adding eggs" should be "The ingredients needed are flour, sugar, and eggs" (all nouns). The phrase "adding eggs" shifts to a verbal form where a simple noun fits. This type of error often occurs because the sentence structure shifts partway through, especially in longer sentences. Identifying the error requires reading the entire list to ensure consistency across all items. On test day, when you encounter a sentence with a list or comparison, pause and scan the items for consistency. If they are not consistent, you have found an error. Most parallel structure questions on the SAT involve this kind of straightforward check: do items in the list match grammatically?

Parallel structure applies to clauses as well as words. "The teacher explained the concept, demonstrated examples, and the students asked questions" is not parallel because the first two items are independent clauses missing a subject (implied subject: "the teacher"), while the third has "the students" as the subject. A corrected version: "The teacher explained the concept, demonstrated examples, and answered questions" (all verb phrases with the same implied subject). Or: "The teacher explained the concept, the teacher demonstrated examples, and the students asked questions" (all complete clauses with explicit subjects), though this is more wordy. When multiple clauses are in a series, ensure they have the same structure. In longer sentences with parallel structure, identifying the pattern (subject-verb-object, for instance) and checking that all items follow it is the most reliable error-spotting strategy.

Parallel structure with "and," "but," and "or" requires special attention because these conjunctions link two or more elements that should be parallel. "The report is detailed but hard to understand" is parallel: both "detailed" and "hard to understand" are adjective phrases describing the report. "The report is detailed but understanding it is difficult" is not parallel because "detailed" is an adjective while "understanding it is difficult" is a clause. A correction: "The report is detailed and difficult to understand" (both adjective phrases). Recognizing the conjunction and checking what precedes and follows it reveals parallel structure errors.

On the SAT, parallel structure questions usually present an underlined portion containing a list or comparison, and you must identify whether the structure is parallel. If not parallel, choose the answer that makes the items consistent in form. Your approach: identify the items in the series or comparison, check their grammatical forms, and note which item breaks the pattern. Then look at the answer choices to see which one fixes the error by making all items parallel. Usually, one answer will stand out as making all items match grammatically. Be cautious of answer choices that change the meaning or introduce new errors while attempting to fix parallelism; the correct answer fixes parallelism without changing meaning or creating other grammar problems. Read each answer choice in context to ensure it is both parallel and correct.

Some parallel structure errors are easier to spot when you read the sentence aloud because parallel items should flow smoothly together. Non-parallel items sound awkward and jarring. Listening for this rhythmic quality helps you identify errors intuitively. On test day, if you are unsure whether a sentence has a parallel structure error, read it aloud and note whether the flow is smooth or choppy. Choppiness often signals faulty parallelism. After you have identified an error, evaluate the answer choices based on whether they smooth the flow and maintain parallel form. The combination of reading aloud, checking forms, and evaluating flow catches most parallel structure errors.