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Interested in or Interested on: Which Preposition to Use

We use prepositions before a noun, pronoun, or noun phrase to show time, direction, place or location, spatial relationships, or to introduce an object. So, do we say “interested in” or “interested on” in English?

“Interested in” is used to indicate the interest (or eagerness) of someone in the subject they want to know more about or the action they wish to perform. The preposition of location or time “in” functions to indicate a state of being that someone is metaphorically “inside of.” Less often, we can use the expression “interested to” followed by a verb of perception. “Interested on” is never correct.

This is one of several combinations of adjectives and prepositions in English that you’ll need to memorize. Read on to further understand the adjective and preposition combinations and what other prepositions we may use in conjunction with the adjective “interested.”

Interested in, Interested to, & Interested on: Which Preposition Is Used after Interested? 

Prepositions are relationship words, and they answer questions concerning where, what, who, and when (source). The British Council of English notes there are some adjectives that go with specific prepositions, and there are no strict grammar rules that dictate which preposition we use with which adjective (source).

Prepositions and Collocations

Preposition collocations are two words — usually a preposition and a noun, verb, or adjective that go together and simply sound correct to a native English speaker. Some can be very difficult to justify, so you’ll need to memorize them as their combination does not change (source). 

There are many cases in the English language where we combine an adjective with a preposition, and “interested in” is one of them (source). Here are a few of the most common combinations of adjectives with the preposition “in”: 

  • Giovanni is interested in classic Italian art. 
  • The teacher was very disappointed in the behavior of her class.
  • She was highly skilled in hockey and soccer.
  • Jeremy is very involved in volunteer work.

Unlike some phrasal verbs, preposition collocations are set, and we cannot insert the object between the adjective and the preposition.

For more on word combinations with prepositions, check out “Appreciation of or for: When to Use Each Preposition in Conjunction with Appreciation.”

How Do You Use “Interested in” in a Sentence?

One such adjective and preposition combination is “interested in,” which is the most common combination for the adjective “interested.”

Let’s take a look at this example:

  • Sally is interested in the project

The preposition “in” connects the subject with the object of the preposition, indicating what has Sally’s interest. The same applies to the following examples where the object (noun) follows the preposition.

  • John is interested in astronomy, so he bought a telescope.
  • The politician’s son was not the least bit interested in politics.

We can also follow “interested in” with a verb that acts like a noun, which we call a “gerund.”

  • I am interested in exploring Mexico.

Prepositions of Location: “In”

Still, what is the rationale for using the preposition “in” with “interested”? The preposition “in” is a positive preposition of location — one of two types that express spatial relations. 

Prepositions of location appear with verbs that describe states or conditions, and one of the prepositions of location that sometimes cause difficulty is “in.”

Spatial (Physical) Prepositions

The preposition “in” indicates that an object lies within the boundaries of an area or within the confines of a volume (source). For example: 

  • My house is in Cape Town  
  • I am in South Africa. 

In these two sentences, the preposition locates the house within a geographical area and the person speaking within a country. Both sentences answer the question of where.

  • There are four rooms in the house and a beautiful fireplace in the bedroom. 

In this sentence, the preposition indicates objects within the confines of a definite volume. It shows two things — the rooms are within the confines of the house, and the object (fireplace) is within the bedroom. 

Time Prepositions

The preposition “in” also functions to describe a lengthy unit of time, such as days, weeks, months, years, or seasons. For example: 

  • The market will be held in the summer. 
  • The United States declared independence in 1776. 

Metaphorical Time and Location Prepositions 

One of the more complicated uses of prepositions is metaphorical prepositions, where we use them to show location or time in metaphorical circumstances. 

Many often think of abstract situations and moods like being in love or pain as something that a person is metaphorically “inside of,” so we often use the preposition “in” for those situations.

The Writing Center for the University of Nevada, Reno, notes that a good way to understand metaphorical prepositions is to think of abstract ideas such as love, states of being, danger, difficulties, or words as being a physical box (source). 

In the following examples, imagine each abstract noun as being a physical box that people can climb into, step out of, or walk through.

  • I am in a bad mood. 
  • Tom and Jane are in love. 
  • He cannot express himself in words.
  • He was the leading researcher in the field of biochemistry. 

“Are You Interested in” Meaning

We can conclude, then, that when someone asks, “are you interested in” something, they’re asking about your condition or state of being. They’re using the preposition in the abstract or metaphorical sense to ask whether you are excited to know more about something, learn more about it, or spend time doing it.

When Do We Use “In” and “On”? 

We can use the prepositions “in” and “on” with nouns to indicate spatial location. However, when we perceive something as a flat surface, then we use  the preposition “on.” When referring to the volume or area of an enclosed space, we use the preposition “in.”

See the examples in the table below to get a better understanding: 

Type of SpaceLocationSentence with PrepositionExplanation
Flat SurfaceField The boys were playing football on the field. 
The field is a flat surface without any fences.  
Flat SurfaceBasketball Court There were six players on the basketball court. 
The court is an open space that is not enclosed — though it might be in an auditorium.
Enclosed AreaBoxing RingThe boxers went ten rounds in the ring. 
The boxing ring is an enclosed space. 
Enclosed AreaFieldThe cows were grazing in the field. The field is an area with fences — it is enclosed. 

For more on the prepositions “in” and “on,” check out our article, “In the Website or on the Website: Using the Right Preposition.”

Do We Say “Interested in” or “Interested on” Buying?

Since we’re using an adjective referring to our state of being when we talk about the desire to buy something, we always say “interested in” instead of “interested on.” For example: 

  • I am interested in buying some property. 
  • I am interested in buying your car. 

However, we might use a phrasal verb like “plan on” with “buying” (source).

  • I plan on buying some property.

Do We Say Interested In or Interested By?

What if something causes you to be interested? Would it be correct to say, “I was interested by it”? No, it would not. However, we could say we were intrigued by something (source).

I was intrigued by her comments yesterday.

This is another collocation you’ll need to memorize.

Interested In vs. Interested To

There is one other preposition that we can use after “Interested.” We can use “Interested to” when “to” functions as part of an infinitive verb — a verb in its “to form.”  Infinitive verbs can function as subjects, objects, or adjectives.

Examples: 

Id be interested to know whether recycling makes a difference to the environment. 

Im interested to see how that turns out.

“Interested to” can function only with verbs of perception and “knowing,” such as “hear,” “see,” “learn,” “read,” “know,” “find out,” etc.  

I am interested to know why she committed the crime.

When someone uses “interested to” in a sentence of the past tense, the expression indicates they have already learned about something and found it interesting.

I was interested to hear that Jake had divorced Sarah.

When we use “interested” with a verb that is not a verb of perception, “interested in” is the only correct option.

Correct:     I am interested in reading.

Incorrect:     I am interested to reading. 

Phrasal Verb: “Interest in” 

While “interested in” is a preposition collocation with an adjective, “interest in” is a phrasal verb. Phrasal verbs consist of a verb and an adverb or preposition, or both, and they’re idiomatic (source). 

This phrasal verb means to attempt to interest someone in something. It can be about a particular subject or an attempt to persuade someone to buy, do, or eat something (source).

Unlike collocations, phrasal verbs can be separable or inseparable. If a phrasal verb is separable, you can separate the two words by placing the direct object in the middle. “Interest in” is a separable phrasal verb that we can therefore separate by placing the direct object in the middle. 

Example: 

  • Can I interest you in our latest vintages? 

Interested vs. Interesting

It’s common for English learners to mix up the adjectives “interested’ and “interesting” when they say, “I am interesting” instead of “I am interested.” Saying, “I am interesting” sounds a tad narcissistic.

The adjective “interested” indicates that someone shows interest in something or wants to learn more about something. The adjective “interesting” means that something arouses curiosity or interest or holds or catches attention — the opposite of boring. This article was written for strategiesforparents.com.

In other words, “interested” describes a feeling of wanting to learn more about something or someone. In contrast, “interesting” describes the thing that makes someone feel that way. You feel interested in something because that thing is interesting (source). 

Consider the following examples that demonstrate how we use  “interesting”: 

  • It was a very interesting book — it kept me in suspense from start to finish. 
  • It was interesting to hear what Tom had to say about the book. 

Notice how the sentences use “interesting” with the preposition “to” plus the infinitive. 

Examples: 

  • It was interesting to meet so many new people at the conference.
  • The documentary was interesting to watch.

Now compare this to how we’ve used “interested”: 

  • Thomas was interested in geography.
  • If you are interested in working in a bank, you should study finance.
  • Are you interested in meeting me for lunch later?

What Does It Mean to Be Interested?

The word “interested” is an adjective that describes showing interest in something and giving it your attention. If you find interest in something, you find it exciting and want to know more about it, or you want to engage in a certain action (source). 

The following examples indicate wanting or not wanting to know more about something.

  • I am very interested in archeology.
  • We would be interested to hear your thoughts on the lesson.
  • I am not particularly interested in history.

In the following examples, someone is asking whether someone wants to do something:

  • Are you interested in joining the art club?
  • There is a presentation on Russian dancing tonight if you are interested.

The adjective “interested” can also mean to be affected or involved — to be in a position to gain from a situation or be affected by it (source). 

  • Several interested parties were eager to get involved in the development. 

Final Thoughts

We have learned that we use the expression “interested in” as opposed to “interested on” as it is a common preposition collocation. It highlights a person’s eagerness to know more about a certain subject or to do something. 

We also discovered that we could use the preposition “to” with “interested” in combination with verbs of perception, like “know” and others.

Make sure you practice these collocations often to memorize them and increase your fluency.