"Flesh out it" is a mistake many advanced learners make without noticing, because the word order looks like it should mirror the noun-phrase version. It doesn't.
"Flesh out" is a separable phrasal verb, and with a pronoun object, separation is mandatory: "flesh it out," never "flesh out it." This isn't a style preference -- "flesh out it" is simply not a grammatical sentence in English.
The rule, and why it only applies to pronouns
With a full noun phrase as the object, both orders are grammatical: "flesh out the plan" and "flesh the plan out" are both correct, though the non-separated order is the more natural default, especially as the object gets longer.
Correct, noun phrase, either order: "Flesh out the proposal before Friday." / "Flesh the proposal out before Friday."
But once that object becomes a pronoun, only one order survives.
Wrong: "Good start -- now flesh out it." Right: "Good start -- now flesh it out."
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Start learning for free →Wrong: "The team asked me to flesh out them before the review." Right: "The team asked me to flesh them out before the review."
Why this slip is easy to make
The error is easy to make because the noun-phrase version genuinely allows "flesh out X," so a learner who's internalized that pattern reasonably assumes it extends to pronouns too. It doesn't -- this is one of the most common patterns in English separable phrasal verbs generally (compare "turn it on," never "turn on it"; "figure it out," never "figure out it"), and "flesh out" follows the same rule. The noun-phrase flexibility is the exception that makes the pronoun rule feel less obvious, not a sign that the pronoun rule is optional.
A simple test to check your own sentence
If the object of "flesh out" is a pronoun -- it, them, this, that -- the pronoun must go between "flesh" and "out." If the object is a full noun phrase, either order works, though putting the object after "out" reads more naturally once the phrase gets longer than two or three words. Before sending a draft, check every "flesh out" for a pronoun object sitting on the wrong side of "out."
Practice scenarios
Practice using flesh out in situations like:
- giving quick feedback with a pronoun object ("flesh it out")
- rewriting a sentence that mistakenly places the pronoun after "out"
- choosing between the two valid orders for a longer noun-phrase object
Useful practice phrases:
- "Good start -- now flesh it out."
- "The team asked me to flesh them out before the review."
- "Flesh out the proposal before Friday." / "Flesh the proposal out before Friday."
With a pronoun, there's only one correct order: the pronoun goes in the middle, every time.
Lyra Practice helps advanced non-native English professionals learn the nuance of high-value workplace expressions and practice using them in realistic scenarios, so their English sounds natural, precise, and senior at work. Try Lyra Practice.