Quick answer: Use “composed of” when describing what parts or materials make up something (the whole consists of these parts). Use “composed by” when crediting the creator of a musical work, poem, or other artistic piece. These phrases are never interchangeable.
These two phrases sound similar but serve completely different grammatical functions. I’ve corrected this exact error in thousands of manuscripts, student essays, and professional documents over my fifteen years as a copy editor. The confusion is understandable—both involve the word “composed”—but mastering the distinction is essential for clear, professional writing.
| Term | Meaning / When to use | Example sentence |
|---|---|---|
| Composed of | Use when listing the parts, ingredients, or elements that form a whole thing | “The committee is composed of seven members from different departments.” |
| Composed by | Use when naming the person who created a piece of music, poetry, or written work | “The symphony was composed by Beethoven in 1808.” |
When to use “composed of”
“Composed of” describes the constituent parts that make up a larger entity. Think of it as answering the question: “What is this made from?” or “What pieces form this whole?” This phrase always points to components, ingredients, members, or elements.
The structure works like this: [Whole thing] + is/are/was/were composed of + [parts]
Here are real examples I encounter regularly in my editing work:
- “The task force is composed of representatives from marketing, sales, and customer service.” (This tells you which departments make up the task force)
- “Water is composed of hydrogen and oxygen atoms.” (This identifies the chemical elements)
- “Her argument was composed of three main points supported by statistical evidence.” (This breaks down the structure)
I see this phrase constantly in technical writing, academic papers, and business reports. For instance, last week I edited a project proposal that originally read “The team is composed by engineers and designers”—a classic error. The corrected version: “The team is composed of engineers and designers.” The team consists of these people; nobody “composed” the team in the artistic sense.
” the term relates to how elements are arranged or combined to form a unified whole, which directly supports the “composed of” usage when describing constituent parts.
More practical examples from actual documents:
- Email signature line error: “Our board is composed by five industry veterans” → Correction: “Our board is composed of five industry veterans”
- Resume mistake: “Managed a department composed by 30 employees” → Correction: “Managed a department composed of 30 employees”
- Text message confusion: “The playlist is composed by 50 songs” → Correction: “The playlist is composed of 50 songs”
Remember: if you can replace “composed of” with “made up of” or “consists of” and the sentence still makes sense, you’re using it correctly.
When to use “composed by”
“Composed by” credits the creator or author of an artistic work, most commonly music but also poetry, essays, or other written compositions. This phrase answers: “Who created this?” It’s exclusively about attribution and authorship.
The structure is: [Creative work] + is/was composed by + [creator’s name]
This phrase appears most frequently in:
- Music credits and album liner notes
- Program notes for concerts and performances
- Academic citations of musical works
- Biographical writing about composers
Examples I correct or confirm daily:
- “The wedding march was composed by Felix Mendelssohn in 1842.” (Credits the composer)
- “This sonata was composed by a student in her final year at Juilliard.” (Identifies the creator)
- “The film score was composed by Hans Zimmer, who won an Academy Award for his work.” (Attributes the music)
The key distinction: “composed by” requires a person (or occasionally a group) as the object, never materials or parts. You would never say “The cake was composed by flour and sugar”—that’s nonsensical because flour and sugar didn’t create the cake; they are the cake’s ingredients.
In my experience editing music journalism and academic papers, this error appears when writers confuse the passive voice construction. For example, I recently fixed a graduate student’s thesis that stated: “The orchestra is composed by strings, woodwinds, brass, and percussion.” Wrong. Corrected to: “The orchestra is composed of strings, woodwinds, brass, and percussion.” But if writing about a specific piece: “The orchestral suite was composed by Gustav Holst between 1914 and 1916.” For more, see Composed.
Real-world corrections from my editing queue:
- LinkedIn bio error: “Our company culture is composed by innovation and collaboration” → Correction: “Our company culture is composed of innovation and collaboration” (these are elements, not creators)
- Concert program mistake: “The quartet was composed by two violins, a viola, and a cello” → Correction: “The quartet is composed of two violins, a viola, and a cello” (instruments are parts)
- Wedding invitation confusion: “The ceremony music was composed of Pachelbel” → Correction: “The ceremony music was composed by Pachelbel” (Pachelbel is the creator)
The meaning of attribution is crucial here. As noted in Wikipedia’s discussion of “Meaning,” the context and relationship between words determines their semantic function—in this case, whether we’re indicating creation or constitution.
How to remember the difference
Here’s the memory trick I teach every student and junior editor: “Of = ingredients, By = creator.”
Say it out loud. Write it on a sticky note. The preposition “of” introduces what something contains; the preposition “by” introduces who made it.
Another powerful technique: use the substitution test.
If you can substitute “made up of” or “consists of,” use composed of:
- “The salad is composed of/made up of lettuce, tomatoes, and cucumbers.” ✓
If you can substitute “written by” or “created by,” use composed by:
- “The song was composed by/written by Taylor Swift.” ✓
Here’s an editor-level insight most people miss: think about agency. “By” introduces an agent—someone who performs an action. In passive voice constructions, “by” always marks the doer. “The book was written by Stephen King.” “The painting was created by Frida Kahlo.” “The symphony was composed by Mozart.” The person has agency; they did something.
“Of” introduces no agency. It simply lists components. The components didn’t do anything; they just exist as parts.
I keep a mental image: a pie chart labeled “composed of” showing slices, versus a concert program labeled “composed by” showing a composer’s name. Visual learners find this particularly helpful.
Common mistakes and exceptions
The most frequent error I see is using “composed by” when describing groups, teams, or collections of things. This mistake appears in business writing, academic papers, and even published journalism.
Wrong: “The study group is composed by students from three universities.” Right: “The study group is composed of students from three universities.”
Wrong: “The dessert is composed by chocolate, cream, and berries.” Right: “The dessert is composed of chocolate, cream, and berries.”
Another common mistake: mixing up “composed of” with “comprised of.” While that’s a separate debate, know that “composed of” is always safe and correct when listing parts. For more, see Meaning.
Regional variations: There are no US vs. UK differences here. Both American and British English use these phrases identically. However, British writers sometimes prefer “comprised of” (though style guides increasingly discourage this), while American editors tend to favor “composed of” or “consists of.”
Exception alert: In very rare poetic or artistic contexts, writers might deliberately bend these rules for stylistic effect. For example, a poet might write “My heart is composed by your love” to suggest that love actively creates or shapes the heart. This is artistic license, not standard usage. Don’t emulate this in professional, academic, or technical writing.
The “comprised” trap: Many writers incorrectly use “comprised of” when they mean “composed of.” Traditional grammar holds that “comprise” means “to include” or “to contain,” so “The whole comprises the parts” is correct, but “The whole is comprised of the parts” is controversial. My advice? Use “composed of” instead and avoid the debate entirely.
One edge case: when a group both consists of members AND was created by someone, you might use both phrases in the same paragraph, but never interchangeably:
- “The jazz ensemble is composed of five musicians. The group’s signature piece was composed by the pianist last year.”
Frequently Asked Questions
Can “composed by” ever refer to non-musical works? Yes. While most common with music, “composed by” can credit the author of poems, essays, letters, or any written composition. For example: “The manifesto was composed by the movement’s founder in 1968.” However, for books and articles, “written by” is more natural.
Is “comprised of” the same as “composed of”? They’re often used interchangeably in casual writing, but traditional grammar distinguishes them. “Composed of” is universally accepted. “Comprised of” remains controversial—many style guides still consider it incorrect. When in doubt, always choose “composed of.”
Can I use “made up of” instead of “composed of”? Absolutely. “Made up of” is a perfect synonym for “composed of” and is actually more common in informal writing. “The committee is made up of volunteers” means exactly the same as “The committee is composed of volunteers.”
Why do native speakers confuse these phrases? Both phrases use the same root word “compose” and sound similar in spoken English. Additionally, passive voice constructions can obscure the difference. The key is remembering that prepositions matter: “of” signals parts, “by” signals the creator.
Tyler Miller is an enthusiastic language analyst with a focus on word comparisons who has spent the past five years contributing to WhichWordHub with insightful content. Graduating with a degree in English Language and Linguistics from the University of Michigan, Tyler quickly developed a keen interest in how subtle differences in word choice can alter meaning and tone. Prior to his current role, he worked as a freelance writer and language tutor, where he gained valuable insights into the varied challenges learners face with English vocabulary. His passion for helping others understand these subtleties inspired him to write extensively on word distinctions and their practical applications. Tyler’s articles often emphasize context-driven language use and the importance of selecting the right word to convey the intended message accurately. He is committed to guiding readers through the complex web of English vocabulary, offering clear explanations and real-world examples to enhance their linguistic proficiency.