Implied Subject Determines Comma

I believe education organizations (e.g., schools, districts, state departments of education) have an obligation to model correct English. Among other responsibilities, they are charged with helping children become successful, contributing members of society, and this means teaching children to communicate well. For this to happen, educators, at all levels, need to demonstrate the highest standard of language use. Children not only learn what they are formally taught but also learn what they observe.

The Sample

With this in mind, I found the following misuse of commas on a school district website.

Once logged in, highlight the Grades menu, and choose Grades to view your student’s current grades. (

This has two commas. The first one is correct, but the second one isn’t.

First Comma: CORRECT

The first comma follows the introductory phrase Once logged in. This comma demonstrates Zen Comma Rule G: Put a comma after introductory clauses and phrases. This phrase is before the subject (i.e., introductory) and describes the main action in the predicate. The comma tells the reader when the introductory phrase ends and when the main sentence is about to begin.

Second Comma: INCORRECT

Now look at the second comma. To understand why it’s wrong, we need to parse this sentence. The subject here is You, which is implied by the imperative (i.e., a command) nature of the sentence. Zen Comma Rule E tells us to use commas as if implied words were present. In this case, we need to add the subject to the sentence to figure out where the commas go or shouldn’t go.

When we put the subject in the sentence, we get this:

Once logged in, you highlight the Grades menu, and choose Grades to view your student’s current grades.

Now that the subject is in place, we see that the sentence has a compound predicate. The sentence has two main verbs and describes two main actions, both of which are linked to the subject You.

Here’s the problem. We don’t separate two parts of a compound sentence with a comma, which this sentence does. To fix this sentence, we need to apply Zen Comma Rule AK: Don’t use commas to separate two parts of a compound predicate. Thus, we remove the second comma.

Need help with commas? Get Zen Comma, a guide to the 17 major uses and misuses of commas. Read more about Zen Comma.


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  1. #1 by Christine on March 6, 2014 - 2:19 pm

    I searched for “comma imperatives compound predicate” and found your blog–love it.

  2. #2 by Jesse Hodge on June 7, 2014 - 11:16 am

    Well said. Thanks for sharing.

  3. #3 by Jen on November 12, 2015 - 3:50 pm

    As far as I can tell, this explanation isn’t in line with CMOS or AP, which consider imperatives to be independent clauses that require commas when separated by conjunctions, at least in most cases. Both allow exceptions for short imperatives that are closely connected, but that isn’t the basis for the explanation given here.

    I’m curious as to why you’ve added “you” as the implied subject to only the first imperative. Is it because of the introductory clause? And if so, then it’s the nature of the sentence (i.e., it has an introductory clause) that’s dictating the treatment of the imperatives, which this explanation doesn’t make clear. One looking for guidance on the general rule for commas with imperatives would come away from this explanation believing you never need commas because “you” is only implied once.

    Here are the examples in CMOS 6.28:

    “Wait for me at the bottom of the hill on Buffalo Street, or walk up to Eddy Street and meet me next to the yield sign.”


    “Raise your right hand and repeat after me.”

  4. #4 by Dan on November 24, 2015 - 3:53 pm

    More than a year later…can I play devil’s advocate? This is something I’ve wondered about. Couldn’t the second part of that sentence also be said to have an implied subject (you), thereby making it another independent clause…thereby necessitating the comma? I’m guessing that’s wrong, but I want to be sure. Thanks!

  5. #5 by Miles on May 3, 2016 - 11:36 am

    If you assume the implied “you” after the introductory clause and subsequent comma, could you not also assume another implied “you” after “and” and before “choose”?

    “Once logged in, YOU highlight the grades menu, and YOU choose grades…”

  6. #6 by Deb Campbell on July 21, 2016 - 11:37 am

    In the “Second Comma: INCORRECT” section, it seems that you did not correctly parse the sentence. It actually consists of two imperative sentences (commands), so you should have inserted the implied “you” subject twice, making it: Once logged in, (you) highlight the Grades menu, and (you) choose Grades to view your student’s current grades. This would make the second comma correct, as it is separating two independent clauses, which both happen to be commands, rather than a compound predicate: “(You) highlight the Grades menu,” and then “(You) choose Grades to view your student’s current grades.”

  7. #7 by Oliver on November 26, 2016 - 3:32 pm

    If we use commas as if implied words were present, then why wouldn’t the sentence be:

    “Once logged in, (you) highlight the Grades menu, and (you) choose Grades to view your students current grades.”

    If both of the implied you’s are included, wouldn’t the second comma be correct? Is there a rule that the implied subject should only be inserted in the first instance?

    Furthermore, can a subject be implied in a sentence like:

    “He begs for his readers’ understanding, and (he) assures them that his comma usage is correct.”?

  8. #8 by Bible in a Year reader on January 18, 2017 - 9:20 am

    The example of the school’s website is giving instructions and separating the steps with commas. Very common for sentence structure since the steps are not laid out using bullets; a) b) c); 1, 2, 3, or any other list method.

    • #9 by preciseedit on September 7, 2017 - 2:29 pm

      If there were three steps, I would agree with you.
      Bullet lists that complete the grammatical structure of the sentence use the same punctuation as the sentence written without bullets. You would not have a comma in this bullet list:

      Once logged in,
      * highlight the Grades menu [no comma] and
      * choose Grades to view your student’s current grades.

      An error does not become correct simply because it is common.

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