Correlative conjunctions are pairs of words that join two elements of equal grammatical value. They create balance in a sentence by linking words, phrases, or clauses that function in the same way. In English, the most common pairs include 'both...and,' 'either...or,' 'neither...nor,' 'not only...but also,' and 'whether...or.' Correct use requires parallel structure on both sides of the pair.

English uses a small set of correlative conjunctions to connect parallel elements. Each pair must appear together in the sentence to create the intended connection. Choosing the right pair depends on the meaning: addition, choice, exclusion, or focus. The pair itself does not change form, but the elements it connects must match grammatically.

Word/Phrase	Definition
both...and	This pair joins two elements to express addition or combination.
either...or	This pair joins two elements to present a choice.
neither...nor	This pair joins two elements to exclude both options.
not only...but also	This pair joins two elements to add emphasis to the second element.
whether...or	This pair joins two elements to present alternatives, often in embedded clauses.

Correlative conjunctions require parallel structure, meaning the joined elements must have the same grammatical form. This can be two nouns, two verbs, two adjectives, two phrases, or two clauses. Maintaining parallelism makes the sentence clearer and more natural in English. Errors often occur when the forms on each side do not match.

Rule
When using correlative conjunctions, connect elements with the same grammatical form.
With 'both...and,' join two parallel items such as nouns or verb phrases.
With 'not only...but also,' keep the structure after each part parallel.
With 'either...or' and 'neither...nor,' make the choices parallel for clarity.

With correlative conjunctions, subject-verb agreement usually follows the noun closest to the verb. This rule is especially important with 'either...or' and 'neither...nor' when joining two subjects. The verb agrees with the second subject because it is nearer to the verb. Agreement also applies to pronouns and possessives linked by the conjunctions.

Rule
With 'either...or' and 'neither...nor,' the verb agrees with the subject closer to the verb.
With 'both...and,' a compound subject takes a plural verb.
With 'not only...but also,' agreement depends on the grammatical subject if subjects are being joined.

Correlative conjunctions do not require special punctuation when joining short elements within a sentence. When each part introduces a clause, a comma may be needed for clarity, especially with longer sentences. Avoid inserting a comma directly between the two parts of the pair. The main goal is to keep the sentence clear and balanced.

Rule
Do not place a comma between the two parts of a correlative pair.
Use a comma when each part introduces a full independent clause and clarity is needed.
Keep punctuation minimal when connecting short words or phrases.