As we’ve learned, adjectives and adverbs act in similar but different roles. A lot of the time this difference can be seen in the structure of the words:

• A clever new idea.
• A cleverly developed idea.

Clever is an adjective, and cleverly is an adverb. This adjective + ly construction is a short-cut to identifying adverbs.

While –ly is helpful, it’s not a universal rule. Not all words that end in –ly are adverbs: lovely, costly, friendly, etc. Additionally, not all adverbs end in -ly: here, there, together, yesterday, aboard, very, almost, etc.

Some words can function both as an adjective and as and adverb:

• Fast is an adjective in “a fast car” (where it qualifies the noun car), but an adverb in “he drove fast” (where it modifies the verb drove).
• Likely is an adjective in “a likely outcome” (where it modifies the noun outcome), but an adverb in “we will likely go” (where it modifies the verb go).

Mistaking Adverbs and Adjectives

One common mistake with adjectives and adverbs is using one in the place of the other. For example:

• I wish I could write as neat as he can.
  • The word should be neatly, an adverb, since it’s modifying a verb.
• Well, that’s real nice of you.
  • Should be really, an adverb, since it’s modifying an adjective

Remember, if you’re modifying a noun or pronoun, you should use an adjective. If you’re modifying anything else, you should use an adverb.

Good v. Well

One of the most commonly confused adjective/adverb pairs is good versus well. There isn’t really a good way to remember this besides memorization. Good is an adjective. Well is an adverb. Let’s look at a couple of sentence where people often confuse these two:

• She plays basketball good.
• I’m doing good.

In the first sentence good is supposed to be modifying plays, a verb; therefore the use of good—an adjective—is incorrect. Plays should be modified by an adverb. The correct sentence would read “She plays basketball well.”

In the second sentence, good is supposed to be modifying doing, a verb. Once again, this means that well—an adverb—should be used instead: “I’m doing well.”

Note: The sentence “I’m doing good” can be grammatically correct, but only when it means “I’m doing good things,” rather than when it is describing how a person is feeling.