Compose vs. comprise: how to use each one correctly

The short answer

Compose means that parts come together to form a whole, so the parts come first in the sentence and the whole comes after. Comprise means that a whole contains or consists of its parts, so the whole comes first and the parts come after. Fifty states compose the United States, but the United States comprises fifty states, two sentences that describe the same fact from opposite directions.

• compose: parts + compose + whole
• comprise: whole + comprises + parts
• avoid: is comprised of, a widely criticized phrase

How compose works

Compose puts the smaller pieces in the subject position and the larger whole after the verb. Twelve musicians compose the orchestra's string section. Water is composed of hydrogen and oxygen atoms, a passive construction that is entirely standard, since composed of correctly places the whole first and the parts after of. Compose also has an unrelated, more common sense meaning to write music or text, as in she composed the song in a single afternoon.

Four departments compose the marketing division, each reporting to a different director. Notice that the parts, four departments, appear first, and the whole, the marketing division, appears after the verb, which is the opposite order from comprise. Keeping this order straight is the fastest way to check whether compose or comprise belongs in a sentence.

How comprise works

Comprise puts the whole in the subject position and lists the parts directly after the verb, with no preposition needed. The committee comprises five elected members and two appointed advisors (not: the committee comprises of five elected members). A single meal can comprise an appetizer, a main course, and a dessert. Because comprise already means to consist of, adding the word of after it is considered redundant and is avoided in careful, edited writing.

The novel comprises three parts, each narrated by a different character. Here the whole, the novel, comes first, and the parts, three sections, follow directly after comprises with no preposition in between. This word order is the clearest signal that comprise, not compose, is the correct verb for the sentence.

Why is comprised of causes trouble

Is comprised of has become extremely common in speech and casual writing, blending the passive form of compose with the meaning of comprise. The team is comprised of ten engineers and three designers sounds natural to many ears, but strict usage guides consider it incorrect, recommending either the team comprises ten engineers and three designers or the team is composed of ten engineers and three designers instead. Knowing this distinction is especially useful for formal writing, editing, and exams.

Remember it

Remember that the whole comprises the parts, and the parts compose the whole, keeping the direction of each verb straight by whichever noun comes first. If you are tempted to write comprised of, pause and ask whether compose would work better in the passive voice instead, since composed of is always correct. Practicing both directions with the same example, like states and country, locks the pattern in quickly.