I'm checking my new formal document with Grammarly, and feel uncomfortable seeing it suggesting I remove the comma in many compound predicates, even in longer ones. For example, the following sentence triggers such a report.

I'm checking my new formal document with Grammarly, and feel uncomfortable seeing it suggesting I remove the comma in many compound predicates.

I Googled for this and was, to be honest, slightly surprised to see all sources posing the same suggestion - no comma should be added in a compound predicate.

To some extent, it conflicts with my "sense of language". I want to know whether my usage of commas in long compound predicates is grammatically correct and whether the suggestion should be strictly followed in a technical document (thesis).

  • Perhaps because you're not a native Anglophone, you need that comma more than most, to help you with the parsing. But without a doubt the general trend for many decades has been towards using "less" punctuation overall (do away with some commas completely, "downgrade" some full stops to commas, etc.). That doesn't mean you have to follow the herd though - you can still make your own stylistic choices. Note that technical documents aren't exactly known for reflecting good stylistic choices (on average technical writers actually tend to make bad choices! :) Commented Apr 4, 2020 at 18:36
  • There is a long debate in English about how to use commas. One camp argues that commas should be used to mark a pause in natural speech. The other camp argues that commas should be used to indicate the underlying sentence structures. Esteemed publishers follow different comma rules, such as the New Yorker Magazine vs. New York Times. Meanwhile in the wider culture, commas are disappearing.
    – SarahT
    Commented Apr 4, 2020 at 20:04
  • You'd do well to check with your mentor whether there are style guidelines you should be abiding by. Grammarly is as useful as any spell checking software; that is to say it's not an authority on English grammar. If commas are part of English grammar, in this case both versions are grammatical.
    – user3395
    Commented Apr 6, 2020 at 15:10

1 Answer 1


First, your sentence is not that long. That length is fine for a thesis.

Second, a comma may very well change what a sentence means, but it does not generally affect the grammaticality of the sentence.

"First, let me say that, while punctuation and grammar are related, details like commas don't generally make something ungrammatical." - JavaLatte (ELL: Grammar, punctuation, comma)

It is a good idea to follow a guideline when you are writing something formal (e.g., academic papers, college applications, official reports, etc.) and then be consistent throughout your work. When you are writing something informal (fiction, emails, ELL answers, etc.), feel free to use punctuation to convey your tone (e.g., comma to denote a pause in speech).

Yes, compound predicates generally do not require a comma before the conjunction.

The Chicago Manual of Style Guide (17th Ed.) says

"A comma is not normally used to separate a two-part compound predicate joined by a coordinating conjunction ... (A compound predicate occurs when a subject that is shared by two or more clauses is not repeated after the first clause.) A comma may occasionally be needed, however, to prevent a misreading." [6.23: Commas with compound predicates]


  • He printed out a week’s worth of crossword puzzles and arranged them on his clipboard.

But compare how this one needs a comma:

  • She recognized the man who entered the room, and gasped.

The MLA Style Center says "Do not place a comma before the conjunction in a compound predicate." The APA Style Blog says "A common mistake people make is to insert a comma between two elements of a compound predicate."

Based on these recommendations from the authoritative style guides, I say you don't need the comma (your sentence is quite straightforward).

Note that "compound predicates of three or more parts treated as a series are punctuated accordingly"; that is, it takes commas just like a series or run-in list (CMoS).

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