‘Interested in doing’ vs. ‘interested to do’ in English

by Jakub Marian

Tip: See my list of the Most Common Mistakes in English. It will teach you how to avoid mis­takes with com­mas, pre­pos­i­tions, ir­reg­u­lar verbs, and much more.

Some English teachers claim that “interested to” is always wrong, but this claim is not substantiated by actual usage. The fact is, the forms “interested in” and “interested to” mean different things and are common even in very formal writing.

“Interested in” is used when referring to a thing you are attracted to or that you would like to do, for example:

I am interested in English literature.

This sentence means that you are attracted to English literature; you find it interesting and would like to know more about it.

On the other hand, “interested to” may be used when you want to obtain more information about a fact, as in

I’d be interested to see whether the new drug helps to cure the disease.

which means

I would like to find out whether the drug helps to cure this disease.

“Interested to” can be used only with verbs of perception and “knowing”, such as:

see, hear, read, learn, know, find out, …

When used in the past tense, the expression means “I found out about it and the information was interesting”, e.g.

I was interested to hear that she had divorced Peter.

which should be understood as

I found out that she had divorced Peter, and I found the information interesting.

In practice, “interested in doing” is much more common than “interested to do”, simply because people usually want to express interest in an activity, as in

correct I am interested in cooking.
wrong I am interested to cook.

When “interested” is used with a verb that is not a verb of perception, “in doing” is the only correct form. When the verb in question is a verb of perception, you should ask yourself, “Is it possible to replace ‘be interested to/in do(ing)’ with ‘want to find out’?” If the answer is yes, it is fine to use “interested to”; if it is no, you should always use “interested in”. For example,

I am interested to know why she committed the crime.

is possible because the intended meaning is “I want to find out why she committed the crime.” Note, however, that many native speakers use “interested to know” and “interested in knowing” in the sense of obtaining information interchangeably and could as well say

I am interested in knowing why she committed the crime.

while others find the second variant less natural and would only use “in knowing” when “know” is used in the sense of “have knowledge of”, as in

I am interested in knowing everything about the English language.

In this case, most native speakers would consider “interested to know” less natural.

By the way, if you haven’t read my guide on how to avoid the most common mistakes in English, make sure to check it out; it deals with similar topics.