11.2 Parallel Structure and Faulty Parallelism

Parallel Structure Basics

Parallel structure means using the same grammatical form for items that serve the same function in a sentence. When you list three activities, compare two options, or connect ideas with conjunctions, each element should follow the same pattern. This keeps your writing balanced, clear, and easy to read.

Faulty parallelism happens when those patterns break. It's one of the most common grammar errors, and it tends to trip readers up because the sentence feels off even if they can't immediately say why. Once you learn to spot it, though, it's straightforward to fix.

Understanding Parallel Structure

Parallel structure repeats the same grammatical pattern to show that items in a sentence carry equal weight. It applies at every level: individual words, phrases, and full clauses.

• Words: "The course is challenging, rewarding, and practical."
• Phrases: "She enjoys playing guitar, writing songs, and recording demos."
• Clauses: "The coach explained what they did wrong, how they could improve, and why consistency matters."

Notice that in each example, every item in the series matches the same form. That consistency is what makes the sentence feel balanced.

Beyond lists, parallel structure also creates rhythm. It's a big part of why famous speeches sound so powerful. Think of "government of the people, by the people, for the people." Each phrase follows the same prepositional pattern, and that repetition makes the line memorable.

Identifying and Correcting Faulty Parallelism

Faulty parallelism occurs when elements that should match grammatically don't. The most common version is mixing different verb forms, noun forms, or phrase structures within a series.

Here's how to spot and fix it:

1. Find the list or paired elements in the sentence.
2. Identify the grammatical form of each element (gerund, infinitive, noun, adjective, clause, etc.).
3. Check whether they match. If one element uses a different form, that's the break.
4. Rewrite the mismatched element so it follows the same pattern as the others.

Example:

The forms here are gerund (swimming), infinitive (to hike), and gerund (biking). Two out of three are gerunds, so the infinitive is the odd one out.

Now all three are gerunds. You could also fix it with all infinitives: "She likes to swim, to hike, and to bike."

Another example:

Here you've got an infinitive phrase, a that clause, and another infinitive phrase. Pick one pattern and stick with it.

Using Coordinating Conjunctions for Parallel Structure

Coordinating conjunctions (and, but, or, nor, for, yet, so) connect elements of equal grammatical weight. Whenever you use one, the items on either side should be parallel.

• Parallel: "The project requires planning, organizing, and executing." (three gerunds)
• Faulty: "The project requires planning, organization, and to execute." (gerund, noun, infinitive)

This rule applies whether you're connecting single words, phrases, or entire clauses:

• Words: "He was intelligent and hardworking." (two adjectives)
• Phrases: "You can find her at the library or in the lab." (two prepositional phrases)
• Clauses: "The data shows that sales increased and that costs decreased." (two that clauses)

A quick test: cover up the conjunction and read each element on its own. If they don't have the same grammatical shape, you've got a parallelism problem.

Employing Correlative Conjunctions in Parallel Constructions

Correlative conjunctions come in pairs: both...and, either...or, neither...nor, not only...but also, whether...or. The grammatical structure after the first word in the pair must match the structure after the second.

The trick is to look at what immediately follows each half of the pair.

• Parallel: "She is both a talented musician and a skilled painter." (a + adjective + noun after each)
• Faulty: "She both is a talented musician and a skilled painter."

In the faulty version, both is followed by a verb (is), but and is followed by a noun phrase. Moving both so it sits right before the noun phrase fixes the mismatch.

More examples:

• Parallel: "Either we go to the movies or we stay home." (full clause after each)
• Parallel: "He not only finished the project but also submitted it early." (verb phrase after each)
• Faulty: "He not only finished the project but also he submitted it early." (verb phrase vs. full clause)

A reliable method: place your finger right after each conjunction word and check that the same type of structure follows both times.

Applying Parallelism

Creating Effective Parallel Lists

Lists are where faulty parallelism shows up most often, especially in professional and academic writing. Every item in a list should begin with the same part of speech and follow the same grammatical pattern.

• Parallel: "The job requires organizing files, answering phones, and scheduling appointments."
• Faulty: "The job requires organizing files, to answer phones, and appointment scheduling."

The faulty version uses a gerund phrase, an infinitive phrase, and a noun phrase. Picking one form and applying it to all three items solves the problem.

This matters just as much in bulleted or numbered lists. If your first bullet starts with a verb, every bullet should start with a verb. If it starts with a noun, they all should.

Constructing Parallel Comparisons

Comparisons highlight similarities or differences between two things, so the two sides need to match grammatically. Watch for this with structures like prefer X to Y, rather than, and more...than.

• Parallel: "She prefers reading books to watching movies." (gerund to gerund)
• Faulty: "She prefers to read books rather than watching movies." (infinitive vs. gerund)
• Fixed: "She prefers to read books rather than to watch movies."

Another common trouble spot:

• Faulty: "Running a mile is harder than to swim a lap."
• Fixed: "Running a mile is harder than swimming a lap."

The rule is simple: whatever grammatical form you use on one side of the comparison, mirror it on the other side.

Maintaining Consistency in Verb Tenses

When verbs appear in a series, they should stay in the same tense unless there's a genuine reason for the shift (like describing events that actually happened at different times).

• Consistent: "He wrote the report, submitted it to his boss, and awaited feedback." (all past tense)
• Inconsistent: "He wrote the report, submits it to his boss, and will await feedback." (past, present, future)

The inconsistent version jumps between three tenses for actions that clearly happened in sequence. Keeping them all in past tense makes the timeline clear.

This also applies within paragraphs. If you start describing a process in present tense ("First, you open the file and review the data"), don't suddenly switch to past tense mid-paragraph without a reason. Unnecessary tense shifts are a form of broken parallelism that can quietly confuse your reader.