If you've ever paused over "comprised of vs composed of" mid-sentence, you're not alone. The two phrases look almost identical in most business writing, and they're treated as synonyms in casual use. But there's a meaningful distinction, and once you see it, you'll catch the error in your own drafts before anyone else does.
The core rule, stated plainly
"Compose" and "comprise" work in opposite directions. The parts compose the whole. The whole comprises the parts. Think of it as a one-way street: "comprise" flows from the big thing down to the small things, and "compose" flows from the small things up to the big thing.
So you'd write: "The committee comprises five members." The whole (committee) comprises its parts (five members). Flip it around and you get: "Five members compose the committee." The parts (members) compose the whole (committee).
Neither of those sentences uses "of." That's the key. "Comprised of" adds an extra word that changes how the verb behaves, and traditional grammar holds that "comprised of" is never correct. The phrase that gets the "of" treatment is "composed of": "The committee is composed of five members."
A quick test you can run on any sentence
When you're not sure which phrase to use, try substituting "made up of." If the sentence still makes sense, use "composed of." If it sounds wrong, reconsider the whole construction.
- "The report is composed of three sections." = "The report is made up of three sections." Works. Keep "composed of."
- "The report is comprised of three sections." = "The report is made up of three sections." Still sounds fine in speech, which is why the error persists. But traditional grammar considers it wrong.
A second test: swap in "constitutes." If you can write "Five members constitute the committee," your original sentence correctly uses "comprises" (not "is comprised of"). The subjects switch, but the logic holds.
Why "comprised of" is so common
The phrase "comprised of" has appeared in print since at least the 18th century. Merriam-Webster now acknowledges it as an established usage, while style guides from the Associated Press and the Chicago Manual of Style still flag it as an error. That split opinion is precisely why the phrase survives: half the world considers it standard, and the other half considers it sloppy. In professional writing, where your credibility is on the line, the safer move is to avoid it entirely.
The confusion also runs deeper than habit. English speakers encounter "composed of" and "comprised of" in similar sentences, and the brain starts treating them as parallel constructions. They aren't. "Composed" is a passive construction (is composed of), while "comprise" is active and doesn't need "of" at all. Mixing the two produces a hybrid that satisfies neither pattern.
How to rewrite sentences that use "comprised of"
You have three clean options when you spot "comprised of" in a draft.
Option 1: Use "composed of." "The team is composed of six engineers and two project managers." This is the simplest fix and works in almost every context.
Option 2: Use "comprises" without "of." "The team comprises six engineers and two project managers." More direct. Preferred by editors who want active verbs.
Option 3: Use "includes" or "consists of." "The team includes six engineers and two project managers." Less precise if you mean the list is exhaustive, but perfectly acceptable in most business contexts.
The choice between options 1 and 2 is often a matter of sentence rhythm. "Comprises" puts the verb in active voice, which is generally stronger. "Is composed of" fits better when you want the passive construction for stylistic reasons, such as when the subject receiving the description is more important than the act of describing it. This is similar to the precision involved in distinguishing objective vs subjective writing: both have their place, but knowing which to deploy matters.
A note on formal business writing
Reports, contracts, proposals, and regulatory filings tend to attract closer scrutiny than internal emails. A reader who spots "comprised of" in a legal brief or a board-level report will likely flag it, even if they can't name the rule. Precision in word choice signals competence. It's the same principle behind getting small things right: the way you handle a phrase like this reflects on the rest of the document.
This is also why tools like Grammarly don't always catch the error. Grammarly flags "comprised of" in some configurations but not others, because the usage sits in a grey zone where descriptive and prescriptive grammar disagree. You can't outsource this one to software.
If you write or edit documents regularly, it's worth building a short personal checklist of constructions that software misses. "Comprised of" belongs on it, alongside confusables like "led" vs "lead", which follow a similarly simple rule that's easy to forget under deadline pressure.
The one-sentence version
The whole comprises the parts. The parts compose the whole. Add "of" only after "composed," never after "comprised." When in doubt, swap in "is made up of" and you'll immediately see which construction fits. That's the test. Run it every time.