In Which, Of Which, At Which, To Which: How to Use Prepositions with Relative Pronouns

English is full of very strange rules that seem to make no sense, and one of those rules is the use of prepositions with relative pronouns such as In Which, Of Which, At Which, To Which.

Prepositions (In, On, At, To) are used with relative pronouns(Which) to indicate a relationship between two clauses when referring to a particular subject. These phrases can be written formally with the preposition in front of the relative pronoun, or with the preposition at the end of the following clause.

Here’s how to use prepositions with relative pronouns.

How Prepositions Work

Prepositions are the part of speech which, when used with a noun or pronoun (or a noun phrase), show an object’s relationship with time and location. They can indicate a place or direction, and spatial relationships.

A common way of explaining directional prepositions is to use the example of a box and how you can relate to it.

I am on the box.
It is in the box.
I can walk to the box.

Prepositions relating to time can be explained as denoting exactly when something happened.

He was born in November.
She gets to work at 9 AM.
We do not work on Saturdays.

What is a Relative Pronoun?

Relative pronouns connect the clauses in a sentence by, as the name implies, relating them to each other. The relative pronouns are

  • Who, referring to a person as the subject of a verb (The girl who took the book is there.)
  • Whom, referring to a person as the object of a verb (The boy whom this toy belongs to is upset.)
  • What, referring to an object or other nonliving thing (What are you looking for in the library?)
  • That, a more general reference (Will the person that parked here please move?)

The relative pronoun we are focusing on is “which.” “Which” refers to an object, a practice, or an event.

The fair, which happens on Saturday, will be fun.
The book, which belongs to Matt, was in the locker.

How to Use Prepositions with Relative Pronouns

Combining these two parts of speech means that you have a phrase that denotes a physical or chronological relationship between a specific subject and the rest of the sentence. In simpler terms, it’s a phrase that can tell you the exact object and where or when it is. Relative pronouns can be used to rewrite two simple sentences into one more complex sentence.

The main relative pronouns are “in which,” “of which,” “at which,” and “to which.”

“In which” refers to the placement of a subject.
The river was cold. They swam in the river.
The river in which they swam was cold.
“Of which” connects a more detailed explanation to the subject.
There has been much discussion about the law. The law will be passed today.
The law, of which there has been much discussion, will be passed today.
“At which” often describes time or an event connected to a subject.
We discussed raises at the meeting. The meeting was long.
The meeting at which we discussed raises was long.
“To which” relates the subject to an action.
I was referring to the card. This is the card.
This is the card to which I was referring.

This format is primarily used in formal English, however. In conversational English, the preposition is often placed at the end of its accompanying phrase, usually (but not always) at the end of the sentence.

The river which they swam in was cold.
The law, which there has been much discussion of, will be passed today.
The meeting which we discussed raises at was long.
This is the card which I was referring to.
Though not technically correct according to standard rules of written English, this format is accepted in informal or verbal English.


Prepositions and relative pronouns used together are a concept that is best learned through trial and error, unfortunately. It’s often a case of getting a feel for what “sounds right,” which may take quite some time if you aren’t a native speaker or aren’t used to using these phrases in everyday settings.

Try to pick out these phrases in your everyday speech and you’ll begin to see patterns in their use. This can help you familiarize yourself with the situations in which they’re used. Mimic these patterns to begin incorporating relative pronouns and their accompanying prepositions into your vocabulary. Eventually, it will become second nature.