Commas with Which, That and Who

The Quick Answer
When do you use a comma with which and who?

(1) Look at the clause that starts with which or who.

(2) If you'd be happy to put brackets around it or delete it, then use a comma.

(3) If you can't put it in brackets or delete it, then don't use a comma.
Here's a slightly longer explanation. If the information provided by the clause introduced by who or which is necessary to identify the person or thing it is describing (i.e., it's not just some extra information you could easily remove), then the clause is not offset with commas. When such a clause (called a relative clause) is necessary for identification purposes, it is called a restrictive clause, and the who or the which can be replaced with that. For example:
  • The car which hit the snowdrift is a write-off.
    • (which hit the snowdrift – restrictive clause, i.e., required to identify the car – not offset with commas)
  • The car that hit the snowdrift is a write-off.
    • (restrictive clause – which can be replaced with that)

When Not to Use Commas with Who and Which

There is often confusion about when to use commas with who and which. Unfortunately, there is no simple rule. Sometimes there should be commas and sometimes there should not. The rule is: When the information provided by the clause is required to identify the person (or thing), then there are no commas.

The examples will make this clearer.

Examples:
  • The boy who broke our window brought some flowers to the door.
    • (The clause who broke our window is required to identify the boy – no commas.)
  • The driver who stole indicator bulbs for his own car was given a formal warning.
    • (The clause who stole indicator bulbs for his own car is required to identify the driver – no commas.)
  • Mr Jeremy Buxton of 16 High Street who was born on the Isle of Wight is the second person from the village to represent England at Cluedo.
    • (The clause who was born on the Isle of Wight is not required to identify Mr Jeremy Buxton of 16 High Street – there should be commas around this clause.)
  • Sarah has always been close to her parents who live in the same village as us.
    • (The clause who live in the same village as us is not required to identify Sarah's parents – comma required before who.)


should be ...parents, who live... (unless she has other parents)
(letter in a newspaper)
  • Experience is a comb which nature gives us when we are bald.
  • The man who doesn't read good books has no advantage over the man who can't read them. (Mark Twain)
  • It is only shallow people who do not judge by appearances. (Oscar Wilde)
  • The man who can dominate a London dinner-table can dominate the world. (Oscar Wilde)
  • One should never trust a woman who tells one her real age. A woman who would tell one that would tell one anything. (Oscar Wilde)
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See Also

Using which, that and who Commas with which, that and who