What Is Parallel Structure and Why It Matters on the GMAT
Parallel structure is a grammatical principle that requires words, phrases, or clauses within a sentence to follow the same grammatical pattern. When elements serve the same function in a sentence, they must be presented in parallel form.
Understanding the Core Principle
Consider this example: "She enjoys reading, writing, and to paint." The structure is not parallel because "reading" and "writing" are gerunds, while "to paint" is an infinitive. The correct version is "She enjoys reading, writing, and painting."
On the GMAT, parallel structure questions test whether you can identify when grammatical forms are inconsistent and know how to correct them. These questions appear in the Sentence Correction section and can be subtle, making them particularly challenging.
Where Parallelism Appears
The GMAT writers frequently test parallelism in these contexts:
- Lists with multiple items
- Comparisons using "like" or "as"
- Comparisons using "than"
- Correlative conjunctions such as "both...and," "either...or," and "not only...but also"
- Paired items connected by coordinating conjunctions
Recognizing these patterns allows you to quickly spot parallelism violations.
Why Mastering Parallelism Matters
Understanding parallelism directly impacts your ability to identify grammatically correct sentences and avoid choosing answers that violate this principle. Many test-takers miss parallelism errors because they focus on other grammar rules or because the errors are embedded in complex sentences. By developing a systematic approach to checking for parallel structure, you catch these errors consistently and improve your verbal score.
Common Parallel Structure Error Types
The GMAT tests several specific types of parallelism errors. Learning to recognize each type helps you develop faster pattern recognition.
List Parallelism Errors
The most common error type occurs when items in a series fail to match grammatically. Example: "The project requires planning, organization, and to communicate effectively." Here, "planning" and "organization" are nouns, while "to communicate" is an infinitive phrase. The correct version is "The project requires planning, organization, and communication."
Comparison Errors with "Like" or "As"
These errors compare a person to a thing, creating a logical problem. Wrong: "Like a skilled musician, the conductor's interpretation was nuanced." This compares a person (musician) to a thing (interpretation). Correct: "Like a skilled musician, the conductor interpreted the piece with nuance."
Correlative Conjunction Errors
These conjunction pairs must have parallel elements: both...and, either...or, neither...nor, and not only...but also. Wrong: "He not only invested in stocks but also in bonds." The structure after "not only" (invested in stocks) does not match after "but also" (in bonds). Correct: "He invested not only in stocks but also in bonds."
Comparison Errors with "Than" or "As...As"
These require comparing like things in like forms. Wrong: "The cost of the new system is higher than the old system." This compares a cost to a system. Correct: "The cost of the new system is higher than that of the old system."
Step-by-Step Strategy for Identifying Parallelism Errors
Developing a systematic approach is essential for consistently identifying and correcting parallelism errors under timed conditions. Follow these five steps.
Step 1: Scan for Signal Words
Look for conjunctions and connecting words like "and," "or," "but," "like," "as," "than," and correlative conjunction pairs. These signal that parallel elements should follow.
Step 2: Identify Parallel Elements
Once you spot a conjunction or comparison word, determine what grammatical elements it connects. Are there multiple items in a list? Are two things being compared? Pinpoint exactly what should be parallel.
Step 3: Examine Grammatical Form
Determine each element's grammatical form. Is it a noun, verb, gerund, infinitive, or clause? Writing out the forms mentally or on your notepad helps solidify your analysis.
Step 4: Check for Consistency
Verify that all elements share the same grammatical form. If they don't, you've found a parallelism error. This is the critical decision point.
Step 5: Select the Parallel Answer
Look at the answer choices to find the option that makes all parallel elements consistent. This might require restructuring how elements are presented, but the core grammatical forms should match.
Tips for Success
Practice this method with sample questions until it becomes automatic. Many students find it helpful to annotate sentences, underlining parallel elements and marking their grammatical forms. This visual approach helps solidify your understanding and develops the intuition needed for test day. The strategy works best when combined with regular practice, which trains your brain to recognize patterns quickly.
Advanced Parallelism Concepts and Edge Cases
Beyond basic parallel structure, the GMAT tests more sophisticated parallelism scenarios that require deeper understanding.
Parallelism with Implied Words
The GMAT expects you to understand what word is implied in a shortened clause. Example: "She enjoyed the novel more than the short story" implies "than [she enjoyed] the short story," which is acceptable. However, "She enjoyed the novel more than he" could mean two different things. The most common reading is "more than he [enjoyed it]," so this structure is typically acceptable.
Mixed Parallel Structures
A sentence might have multiple levels of parallelism that must all be correct simultaneously. Example: "The committee decided not only to approve the proposal but also to fund the subsequent research and development." You must check that both main parallel elements (approve the proposal and fund the research and development) are parallel, and the internal parallelism (research and development) is also correct.
Parallelism with Prepositional Phrases
Consider whether prepositions need to be repeated for clarity. Example: "He was interested in both the scientific approach and practical applications." Check whether "in" applies to both elements or needs repetition. The GMAT generally accepts implied prepositions when they apply logically to all elements, but clarity is crucial.
Unnecessary Repetition Issues
The GMAT occasionally tests whether unnecessary repetition breaks parallelism. Repeating a word unnecessarily can sometimes disrupt the parallel structure's elegance, though grammatically it may be acceptable. Understanding these nuances helps you navigate complex sentences where multiple principles interact.
Why Flashcards Are Effective for Mastering Parallel Structure
Flashcards are particularly effective for learning parallel structure because this topic requires pattern recognition, repetition, and the ability to internalize grammatical rules. The GMAT tests parallelism frequently but in varied contexts, making exposure to multiple examples crucial.
Building Pattern Recognition
Flashcards allow you to study example sentences systematically, building your pattern recognition muscles. Each flashcard can present a sentence containing a parallelism error on one side and the correction with an explanation on the other. By repeatedly reviewing these examples, your brain develops the ability to automatically spot violations.
Spaced Repetition Advantage
Spaced repetition, a core feature of effective flashcard systems, ensures you review difficult concepts more frequently than mastered ones. This is ideal for parallelism, where some error types (like basic list parallelism) may become intuitive quickly, while others (like correlative conjunction parallelism) might require longer practice.
Flexible, Anywhere Learning
Flashcards allow you to study anywhere, anytime, making it easy to fit parallelism practice into your busy schedule. Rather than completing long practice sets all at once, you can review a few cards during breaks, reinforcing learning throughout the day.
Active Recall Strengthens Memory
The active recall process of retrieving information from memory strengthens neural connections more effectively than passive reading. When you try to identify an error and then verify your answer, you engage your brain more deeply than simply reading explanations.
Customization to Your Needs
Flashcards can be customized to your needs. You can focus heavily on the error types that trouble you most while maintaining knowledge of easier concepts. Many successful GMAT students use flashcard systems as their primary study tool for grammar concepts, often combined with full-length practice tests to develop speed and accuracy under timed conditions.