Parallelism in Sentences

Faulty parallelism is what happens when a sentence sets up a pattern, a list, a comparison, or a pair joined by a conjunction, and then breaks that pattern partway through. You already know from studying parallel structures that matching grammatical forms creates balance. This lesson shifts the focus from recognizing correct parallelism to actively hunting down and repairing the places where writers, including you, most often let it slip: series of items, comparisons, and compound sentence elements.

A sentence has faulty parallelism when two or more elements that function the same way in the sentence, such as items in a list or the two sides of a comparison, are written in different grammatical forms. The reader expects consistency once a pattern begins, so a shift in form (from a gerund to an infinitive, from a noun phrase to a full clause) creates a stumble that a reader has to mentally repair.

Consider: "The coach values discipline, teamwork, and to compete fairly." The first two items are nouns, but the third switches to an infinitive phrase. The fix is to make all three items the same part of speech: "discipline, teamwork, and fair competition."

Lists are the most common site of faulty parallelism because a writer often starts a series with one structure and drifts into another while adding items. Watch for shifts between gerunds (-ing forms), infinitives (to plus a verb), and plain nouns within the same series.

Faulty: "Her weekend included hiking, biking, and she read three chapters."
Corrected: "Her weekend included hiking, biking, and reading three chapters."

To correct a faulty list, isolate each item, name its grammatical form, and rewrite every item to match the form used by the majority or the form that reads most naturally.

Comparisons built with "as...as," "than," or "compared to" require that the two things being compared share the same grammatical form, and, just as importantly, that the comparison is logically sound. A comparison can be grammatically parallel yet still confusing if it compares two unlike categories.

Faulty: "Studying chemistry is more demanding than history."
Corrected: "Studying chemistry is more demanding than studying history."

The uncorrected version technically compares "studying chemistry" (an activity) to "history" (a subject), which is a mismatch in both grammar and logic. Repeating the parallel word "studying" restores balance and makes the comparison precise.

Compound elements joined by coordinating conjunctions ("and," "but," "or") or correlative conjunction pairs ("either...or," "neither...nor," "not only...but also") must place matching grammatical structures immediately after each part of the pair.

Faulty: "She not only enjoys painting but also to write poetry."
Corrected: "She not only enjoys painting but also writes poetry."

Notice that the corrected sentence places a verb phrase ("enjoys painting") after "not only" and another verb phrase ("writes poetry") after "but also," so the structure lines up on both sides of the pair.

When you edit a sentence for parallelism, work through these steps:

1. Locate the coordinated elements, whether they appear in a list, a comparison, or a pair joined by conjunctions.
2. Identify the grammatical form of each element (noun, gerund, infinitive, clause, adjective).
3. Choose one form to apply consistently, usually the form used by most of the elements already.
4. Rewrite the mismatched elements so every part of the structure matches.
5. Reread the sentence to confirm it is both grammatically parallel and logically sound, since matching forms alone will not fix a comparison between unrelated ideas.

Building this editing skill takes deliberate practice with sentences drawn from your own writing as well as guided exercises. Resources such as parallel structure in writing and parallelism usage rules offer additional practice for applying these correction strategies across different sentence types.

Related lessons

• Parallel Structures