A compound subject is a subject that contains two or more parts joined by a conjunction — and, or, nor, or a correlative pair like either...or and neither...nor. The conjunction you choose determines whether the verb is singular or plural.
The same two people, but a different conjunction changes the verb completely. The three core rules below cover every compound subject you will encounter.
Joined by "and"
Two or more subjects joined by and almost always take a plural verb — regardless of whether each individual subject is singular.
This is the most predictable rule in compound subjects: and adds things together, so the result is plural.
When "and" means one thing
There is one exception. When two nouns joined by and describe a single concept rather than two separate things, the verb is singular.
The test is simple: if you can replace the whole phrase with it and the meaning survives, it is a single concept. Fish and chips is one dish, not a plate of fish next to a plate of chips. The bed and breakfast is one business, not a bed plus a breakfast.
Compare:
Context decides. The same words can go either way.
"Each" and "every" before compound subjects
When each or every stands before subjects joined by and, the verb becomes singular — each item is considered individually.
Joined by "or" / "nor"
Subjects joined by or or nor follow a different logic. The conjunction presents alternatives, not a sum — only one of the subjects actually does the action.
Both subjects are the same number
If both subjects are singular, the verb is singular. If both are plural, the verb is plural.
Subjects differ in number — the proximity rule
When one subject is singular and the other is plural, the verb agrees with the subject nearest to it.
Both sentences are grammatically correct. In practice, placing the plural subject closer to the verb sounds more natural. If a sentence feels awkward, rearrange it so the plural part comes last.
"Either...or" and "neither...nor"
These correlative pairs follow the same rules as plain or and nor.
Two singular subjects — singular verb:
Mixed singular and plural — proximity rule:
The pair not only...but also works the same way:
Phrases that look like "and" but are not
Several common phrases seem to add a second subject the way and does, but grammatically they do not. The verb agrees with the first subject only.
These phrases include: along with, together with, as well as, in addition to, accompanied by.
The phrase between the commas is extra information — a parenthetical addition — not a true part of the subject. If you want a genuine plural subject, rewrite with and:
Common mistakes
"And" with a plural verb forgotten
Single concept treated as plural
"Or" / "nor" — proximity rule ignored
"As well as" treated like "and"
"Each" / "every" with a plural verb