Most of the time, the choice between a gerund (reading) and an infinitive (to read) is not about the verb at all. It's about what comes before the blank.
A preposition, an adjective, or a noun each pulls one specific form. Once you recognize the slot, the form is automatic — you don't have to remember a list.
This lesson covers those positional rules, the purpose contrast to / for, gerunds used as the subject, and the small group of verbs that accept both forms with no change in meaning.
After a preposition → gerund
Any word that ends in a preposition forces the -ing form on whatever verb follows.
This covers prepositions after adjectives (good at, interested in, tired of), after verbs (think about, rely on, dream of), and standalone (before, after, without, instead of, by).
The test is simple: if the word before the blank is a preposition, the verb takes -ing. No exceptions worth remembering.
After an adjective → to-infinitive
When a verb follows an adjective directly (no preposition in between), the form is to + infinitive.
The same rule holds for the patterns too + adjective and adjective + enough.
Quick contrast with the preposition rule above:
| BEFORE THE VERB | FORM |
|---|---|
| good at | painting |
| good | to see you |
| interested in | learning |
| eager | to learn |
After a noun → to-infinitive
When a verb modifies a noun — answering "what kind?" or "for doing what?" — the form is to + infinitive.
This is the source of many fixed phrases: a reason to believe, the chance to travel, a decision to make, something to drink.
Purpose: *to* vs *for*
Both to and for can express purpose, but they follow different rules. Mixing them up is one of the most frequent mistakes at this level.
To + infinitive expresses the purpose of an action — why someone does something.
For + gerund expresses the purpose of an object or tool — what something is used for.
The two patterns look similar but cannot be swapped.
A useful check: if the subject is a person doing something, use to + infinitive. If the subject is a thing with a function, for + gerund works too.
Gerund as the subject
When a verb starts the sentence as the subject, use the gerund.
The infinitive can technically appear as a subject (To err is human, To travel is to live), but it sounds literary or proverbial. In ordinary modern English, the gerund is the natural choice.
Verbs that take both forms with no meaning change
A small group of verbs — mostly about likes, preferences, and the start or end of activity — accept either form with essentially the same meaning.
- like, love, hate, prefer
- begin, start, continue
There is a faint stylistic nuance: the -ing form leans slightly toward general enjoyment or ongoing activity, and the to-form leans toward a habit or preference in principle. The difference is small and rarely affects communication.
Both are correct. At this level, you can use either without worry.
A note of caution: many other verbs change meaning depending on the form (stop, remember, forget, try, regret, mean). Those are covered separately.
Common mistakes
Preposition + verb
Purpose: to vs for
Gerund as subject
Adjective + verb
Noun + verb