Parallel Structure

Try reading this at normal speed: “She liked hiking, to swim, and reading.” Something in it snags, even though every word is spelled correctly and every clause technically makes sense. Where does the stumble come from?

It comes from the list itself. “Hiking” and “reading” are both -ing forms, but “to swim” switches shape halfway through, and a reader’s ear notices the mismatch even when their eye reads right past it. Fix it by making all three match — “She liked hiking, swimming, and reading” — and the sentence stops snagging, because now every item is doing the same grammatical job.

Why a small mismatch matters this much

This is called parallel structure: the items in a list, or the two sides of a comparison, using the same grammatical form. It shows up in comparisons too. “The village was small, quiet, and had a lot of history” breaks the pattern the same way the hiking sentence did — two adjectives followed by a whole verb phrase — while “The village was small, quiet, and steeped in history” keeps all three describing the village the same way.

What makes broken parallel structure tricky is that it’s often a mismatch a reader feels without being able to name. Nobody stops mid-sentence and thinks “that’s not parallel” — they just sense that something sounds slightly clumsy, without knowing why. Fixing it is almost always a matter of rewriting one item so its grammatical shape matches the others, which is a small habit that makes the difference between a sentence that reads like an early draft and one that reads like it was written on purpose.