Introduction
You know "and," "or," and "but" — the basic connectors. Correlative conjunctions are their more precise cousins: pairs of words that work together, one signaling what's coming and the other completing the thought — not only...but also, neither...nor, either...or, both...and.
They exist because plain "and" and "or" are a bit vague about the logical relationship between two ideas. "Not only...but also" says "here's one thing, and — brace yourself — there's more." "Neither...nor" firmly shuts the door on two options at once. Used well, these pairs make your writing feel tightly organized and deliberate. Used carelessly, they're one of the easiest ways for an advanced sentence to quietly fall apart — usually because the two halves don't actually match, or the verb doesn't agree with the subject it's supposed to. That's exactly what this page is here to fix.
The Core Forms
Both...and — addition
Both the manager and the team were praised for the launch.
Either...or — choice
Either she calls us back today, or we'll have to move on without her.
Neither...nor — double exclusion
The company neither apologized nor offered a refund.
Not only...but also — emphatic addition
Not only did the team finish early, but they also came in under budget.
Notice that last example: when "not only" opens the whole sentence and introduces a full independent clause, the subject and auxiliary flip places, exactly like the negative-adverbial fronting you may already know from the Fronting and Preposing page. More on exactly when that applies in the next section.
The Real Rule: Why This Doesn't Generalize
Whatever grammatical form follows the first half of the pair must be mirrored exactly after the second half — this is called parallel structure, and it isn't optional polish, it's part of what makes the sentence work. If the first half is followed by a noun phrase, the second half needs a noun phrase too; if it's a verb, an infinitive, or a prepositional phrase, the second half needs the same. "She not only enjoys reading but also to write poetry" breaks this — a gerund on one side, an infinitive on the other.
For either...or, neither...nor, and not only...but also, the verb agrees with whichever subject sits closest to it — usually the second one. "Neither the manager nor the employees were informed" takes "were" because "employees" (plural) is the nearer subject; "Neither the employees nor the manager was informed" takes "was" because "manager" (singular) is now the nearer one. Both...and is the odd one out here: since it genuinely adds two subjects together, it always takes a plural verb, regardless of which noun sits closer. "Both the manager and the assistant were present" — always "were," never "was."
The pair has to sit directly in front of the exact elements being compared — not just somewhere earlier in the sentence that happens to sound acceptable. "The mall requires not only wearing face masks but also face shields" misfires because "not only" ends up governing "wearing face masks" (a verb plus object) while "but also" only has "face shields" (a bare noun phrase) to work with. Moving "not only" to sit right before "face masks" fixes it: "The mall requires wearing not only face masks but also face shields."
The subject-auxiliary flip with "not only" is conditional, not automatic. It only happens when "not only" opens the entire sentence and introduces a full independent clause: "Not only did she finish early, but she also came in under budget." When "not only" sits in the middle of a sentence, connecting two smaller elements like verbs or objects, there's no flip at all: "She not only finished early but also came in under budget" keeps normal subject-verb order throughout.
"Neither...nor" already carries its own negation built in — it doesn't need, and can't take, an extra "don't/doesn't/isn't" alongside it. "He doesn't like neither tea nor coffee" stacks two negatives on top of each other and muddles the meaning. The negation belongs to "neither" alone: "He likes neither tea nor coffee."
Common Errors
Error 1 — Breaking parallel structure.
✓ She not only enjoys reading but also writes poetry.
Error 2 — Getting proximity agreement wrong.
✓ Neither the manager nor the employees were informed.
Error 3 — Forgetting that "both...and" is always plural.
✓ Both the CEO and the board were informed.
Error 4 — Placing the pair before the wrong element.
✓ The mall requires wearing not only face masks but also face shields.
Error 5 — Doubling up the negation with "neither...nor."
✓ He likes neither tea nor coffee.
Error 6 — Adding the inversion when it isn't triggered.
✓ She not only sang but also played guitar.
Error 7 — Forgetting the inversion when it IS triggered.
✓ Not only did she finish the marathon, but she also broke the record.
Register and Usage
"Both...and" and "either...or" are completely neutral — equally at home in casual conversation and formal writing. "Neither...nor" is also common in both, though it leans slightly more formal than its everyday spoken equivalent: "I don't like tea or coffee" is how most people would actually say "I like neither tea nor coffee" out loud.
"Not only...but also" is the most clearly elevated of the four. It shows up constantly in academic writing, business reports, and formal speeches, where its job is to build a small rhetorical crescendo — here's a solid first point, and here's an even better second one. Overusing it in casual conversation can sound a little performative, the way constantly speechifying in an everyday chat would.
Don't Confuse This With: Standalone "Nor" and "Either...Or" vs. "Neither...Nor"
"Nor" doesn't only show up paired with "neither." On its own, after a complete negative clause, it can introduce a second negative clause — and when it does, it triggers the same kind of subject-auxiliary inversion "not only" does when it opens a sentence: "I don't enjoy horror movies, nor do I enjoy thrillers." "She wasn't informed, nor was she consulted." This is a different structure from paired "neither...nor," which connects two elements inside a single clause rather than linking two separate independent clauses together.
It's also easy to mix up "either...or" and "neither...nor" simply because they look like structural twins. They express opposite ideas: "either...or" presents a choice where at least one option holds true, while "neither...nor" flatly rules both options out. Reaching for the wrong one doesn't just sound odd — it reverses your meaning entirely.
Exercises
Exercise 1 — Transformation
Combine each pair of sentences into one, using the correlative conjunction given. Keep the two halves grammatically parallel.
Exercise 2 — Error Correction
Each sentence contains one mistake. Find it and type the sentence correctly.
Exercise 3 — Multiple Choice
Choose the correctly formed sentence.
1.
2.
3.
4.
5.
6.
Exercise 4 — Key Word Transformation
Complete the second sentence so that it means the same as the first, using the key word given. The key word must not be changed in any way.