Conjunctions: Coordinating, Subordinating and Correlative (With Examples and Comma Rules)

A conjunction is a word that joins words, phrases or clauses. English has three kinds: coordinating (for, and, nor, but, or, yet, so), subordinating (because, although, if, when) and correlative pairs (either/or, not only/but also). Each kind has its own punctuation: a comma before a coordinating conjunction joining two full clauses, and a comma after an opening subordinate clause.

What is a conjunction?

A conjunction is a word that connects two things of the same kind or links a dependent idea to a main one. It can join words ("tea and coffee"), phrases ("in the morning or in the evening") or whole clauses ("I wanted to leave, but the train was cancelled"). It does not change form: it has no plural, tense or case.

English grammar books sort conjunctions into three groups, and the group tells you both what the word does and how to punctuate it.

Words like "however", "therefore" and "moreover" are often mistaken for conjunctions. They are conjunctive adverbs, which have different punctuation rules; see the section on them below and our transition words guide.

Coordinating conjunctions and FANBOYS

There are seven coordinating conjunctions. The memory aid FANBOYS gives you all of them:

• For: gives a reason (formal, mostly literary): "She stayed, for the roads were closed."
• And: adds: "We wrote the draft and edited it."
• Nor: adds a negative to a negative: "He did not call, nor did he write."
• But: contrasts: "The plan is simple, but the budget is tight."
• Or: gives a choice: "Submit it online or bring a printed copy."
• Yet: contrasts with a sense of surprise: "The essay was short, yet it was persuasive."
• So: gives a result: "The lecture was cancelled, so we went to the library."

Coordinating conjunctions join elements that have the same grammatical weight: two nouns, two verbs, two phrases or two independent clauses. "Nor" normally causes the word order after it to invert (a verb before the subject), as in "nor did he write".

Punctuation with coordinating conjunctions

The rule is about what is on each side of the conjunction.

The comma between two independent clauses is the one most writers ask about. It is standard in both American and British style guides when the clauses are of reasonable length, and it can be omitted when the clauses are very short and closely linked ("I came and I saw"). A sentence with a comma where there is only one clause ("She opened the file, and read the notes") is a common over-use. For lists, see the Oxford comma guide, and for more on commas generally, comma rules. A detailed look at the seven words is in coordinating conjunctions.

Can you start a sentence with "and" or "but"?

Yes. The idea that it is wrong is a school-room rule of thumb, not a rule of English grammar. Major usage guides, including Merriam-Webster's Dictionary of English Usage and Fowler's Dictionary of Modern English Usage, accept sentences beginning with "and", "but" or "so", and the Chicago Manual of Style, which many publishers follow, says plainly that there is no rule against it. Use it for emphasis or rhythm, and keep it for contrast or continuation that really needs its own sentence. In very formal academic prose, some instructors prefer "however" or "moreover" instead, so check your handbook. Do not put a comma directly after the opening "But" or "And" unless a parenthetical element follows.

The results were clear. But the sample was small.

Do you put a comma before "and"?

Only when "and" joins two independent clauses, or in a list if your style uses the serial comma.

• "She wrote the introduction, and he wrote the conclusion." (two clauses: comma)
• "She wrote the introduction and revised the conclusion." (one subject, two verbs: no comma)
• "We tested the tool, the prompt, and the output." (list: comma in Oxford style; omitted in many British and AP-style texts)

Subordinating conjunctions

A subordinating conjunction introduces a dependent clause: a group of words with a subject and a verb that cannot stand alone. The dependent clause needs a main clause to complete it.

Punctuation with subordinating conjunctions

The test is simple: when the dependent clause comes first, a comma tells the reader where the main clause begins. When it follows the main clause, no comma is needed unless the contrast is sharp. A subordinator that opens a sentence needs a main clause, or you have a fragment ("Because the server was down."). For more on the clause types, see independent vs dependent clauses and complex sentences.

Correlative conjunctions

Correlative conjunctions come in pairs and join equal elements. Both halves must be present, and the words after each half must have the same grammatical form. This matching is called parallel structure.

The parallelism trap

Put the pair immediately before the items it connects.

• Wrong: "She not only wrote the essay but also the abstract." (the first half is before the verb; the second before a noun)
• Right: "She wrote not only the essay but also the abstract."
• Right: "She not only wrote the essay but also edited the abstract."

Agreement with neither...nor and either...or

When two subjects are joined by "nor" or "or", the verb normally agrees with the subject nearer to it: "Neither the students nor the teacher was available" and "Neither the teacher nor the students were available". Many writers avoid the awkwardness by putting the plural subject last. For general agreement rules, see subject-verb agreement.

Conjunctive adverbs are not conjunctions

"However", "therefore", "moreover", "otherwise", "consequently" and "nevertheless" show how two ideas relate, but they cannot by themselves join two independent clauses. Joining them with only a comma creates a comma splice:

• Wrong: "The test was hard, however I passed."
• Right: "The test was hard; however, I passed."
• Right: "The test was hard. However, I passed."
• Right: "The test was hard, but I passed."

The semicolon rule is covered in when to use a semicolon. A useful habit: if you can swap the word for "but" and the sentence still works with a comma, "but" is the better fit.

Before and after: fixing conjunction problems

Comma splice. Before: "The library closes at six, I will finish my essay tomorrow." After: "The library closes at six, so I will finish my essay tomorrow."

Missing comma after an opening clause. Before: "When the results arrived the committee met." After: "When the results arrived, the committee met."

Unneeded comma before a subordinate clause. Before: "We postponed the meeting, because the speaker was ill." After: "We postponed the meeting because the speaker was ill."

Fragment. Before: "Although the proposal was strong." After: "Although the proposal was strong, the funders asked for changes."

Faulty parallelism. Before: "The role requires both writing reports and to manage a small team." After: "The role requires both writing reports and managing a small team."

What the style guides say about common questions

Style guides agree on the core rules and differ on small points. This table summarises the tendencies; check your own guide when it matters, as they can differ on details.

If you are writing for a university, your department's style guide (APA, MLA, Chicago or Harvard) takes precedence. In a workplace, follow the house style. Our guides on sentence structure and parts of speech give the wider grammar context.

Quick quiz

Choose the best answer, then check below.

1. "I wanted to attend ___ I was ill." (but / because / so)
2. "She is ___ talented ___ hardworking." (not only / but also; both / and)
3. "The proposal was weak ___ we rewrote it." (so / although / either)
4. Which is correct? "The train was late, however we arrived on time." or "The train was late; however, we arrived on time."
5. Does this need a comma? "He locked the door and left."

Answers: 1. but (contrast: "but I was ill"). 2. both...and, or not only...but also; both are correct. 3. so (result). 4. The second; the first is a comma splice. 5. No, because "locked the door" and "left" share one subject.

A checklist for any sentence with a conjunction

1. Is the conjunction coordinating, subordinating or correlative?
2. If coordinating and joining two independent clauses, is there a comma before it?
3. If a subordinate clause opens the sentence, is there a comma after it?
4. If correlative, are both halves present and followed by the same grammatical form?
5. Is there a word like "however" or "therefore" being used as if it were a conjunction?
6. Is the sentence a fragment because it starts with a subordinator and has no main clause?
7. Are there too many "and"s in a row?

Using AdeptWrite to practise and check conjunctions

The Grammar Checker checks grammar, spelling and punctuation and shows every change it suggests, so you can see where a comma has been added or a fragment flagged and decide whether to accept it; the final judgement on style is yours. The Sentence Rewriter can help when a sentence is tangled by too many linked clauses, with Standard and Formal modes. The Paraphrasing Tool offers several modes, including Standard and Formal, for rewording a passage, and you should read the result carefully because a rewrite can change the conjunction and with it the meaning. Run text through each tool in turn if you are editing a long draft, and keep the 6,000-character limit per run in mind.

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