Use like before a noun or a pronoun ("She sings like a bird") and as before a clause with its own verb ("Nobody bakes as Mom does"). As before a noun means "in the role of" ("She works as a nurse"), which is not a comparison at all.
Read these two sentences:
Tim is a grown man who often acts as a child whenever he sees a sports car. Just as his late father, Tim has always loved fast cars.
Do they sound odd to you? That is because they are wrong: they mix up like and as. Tim acts like a child, and like his late father, he has always loved fast cars.
Like vs. as: what is the difference?
Mixing up like and as is a very common grammar mistake. Both words can mean "in the same way", but they are not always interchangeable.
In a comparison, like is a preposition: it comes before a noun, a noun phrase, or a pronoun. As is usually a conjunction: it joins two clauses, so a subject and a verb follow it. (For more on words that join clauses, see conjunctions in English grammar.)
| Word | Followed by | Example |
|---|---|---|
| like | a noun, noun phrase, or pronoun | He growls like a tiger. |
| as (comparison) | a clause: subject and verb | He growls as a tiger does. |
| as (role) | a noun | He works as a zookeeper. |
When to use like
Use like plus a noun, a noun phrase, or a pronoun to compare things:
He growls in his sleep just like a tiger.
This sentence compares the way the man growls in his sleep with a tiger. Here are some more examples:
Like all good dogs, Jerry never fails to bark at the postman.
You are such an artist, just like your father and grandfather.
That cloud looks like a rabbit.
When to use as
Use as plus a clause when you want to say that something happens in the same way as something else. If you are not sure whether to use as or like, try replacing the word with "the way".
Here is an example:
Nobody makes apple pie as Mom does.
Nobody makes apple pie the way Mom does.
"The way" fits in the place of as, and the sentence still makes sense. So as is the right choice.
Context matters
Before you correct someone else's grammar, remember that context matters. Look at these two sentences:
Martin is acting like a kid.
In the school play, Martin appears as a kid.
Which of them is wrong? Neither. You might say the first one about an adult who throws a tantrum in public: he is not a kid, but he behaves like one. The second one is right too, because here as means "in the role of": Martin plays the part of a kid. In the same way, "she spoke like a lawyer" means she sounded like one, while "she spoke as a lawyer" means she is a lawyer and spoke in that role.
Like as a conjunction in informal English
To make things harder, in informal English many people use like as a conjunction, before a clause. So if a character in your novel says this:
Nobody drifts like he does.
it is perfectly fine in dialogue, even though formal grammar asks for as here. In formal writing, such as an essay, a report, or a job application, use as before a clause.
If telling like and as apart is hard for you, check your text before you send it. The Spell Checker checks grammar as well as spelling, and the AI Spell Checker reads whole sentences, so it can also catch a real word in the wrong place.