It’s well known that introductory phrases should be followed by commas. Here is an example:

To stay in shape for competition, athletes must exercise every day.

Consider now the following two sentences:

In the best case, it is like this. In the worst case, it is like that.

Suppose one wishes to write them in one sentence using the coordinator and. What is the right way to punctuate this new sentence?

  1. In the best case, it is like this, and in the worst case, it is like that.

  2. In the best case, it is like this, and, in the worst case, it is like that.

Another example that I often stumble upon is the following:

  1. It is like this, and therefore, it is like that.

  2. It is like this, and, therefore, it is like that.

What is preferable: sentences 1 and 3 or sentences 2 and 4? Is there some rule in this regard?

  • The comma after "and" is optional. Do you intend for the reader to pause there?
    – Davo
    Commented Oct 31, 2017 at 22:03
  • @Davo, could you please provide a reference for this, such as a style manual? It doesn’t have to address this case directly, but it’d be reassuring to see such constructions used by a reputable source.
    – Ivan
    Commented Nov 1, 2017 at 4:52

1 Answer 1


In general, guides on using commas specify that (unless being used to set off parenthetical expressions) commas should not be used following conjunctions.

Some sources: Grammarbook.com, and this ELU thread, and especially this ELU thread, which quotes the Gregg Reference Manual, 10th Edition, section 142b:

When the [transitional] expression or comment occurs at the beginning of the second independent clause in a compound sentence and is preceded by a comma and a coordinating conjunction, use one comma following the expression.


In the first place, I think the budget for the project is unrealistic, and in the second place, the deadlines are almost impossible to meet.

However, there is some general acceptance of varying from these rules to indicate a pause and/or for greater clarity.

Some sources: This ELU thread, this ELL thread, Writersrelief.com, and Writing-skills.com.

  • Sorry, I’m probably missing something. I haven’t found sentences such as mine in the references you provided. I’m looking for the following pattern: “<independent clause 1>, <coordinator> <introductory phrase>, <independent clause 2>” so that <introductory phrase> and <independent clause 2> would typically be separated by a comma if they were the only ones in the sentence. The question is in what is in between <coordinator> and <introductory phrase>.
    – Ivan
    Commented Nov 1, 2017 at 13:15
  • "In the best case, it is like this." is a complete sentence, and "In the worst case, it is like that." is a complete sentence. Why should your two complete sentences, joined with a conjunction, be a special case? Why would it be different from any other two complete sentences joined with a conjunction?
    – Davo
    Commented Nov 1, 2017 at 13:35
  • I’m just learning English, and I don’t know if there is a different, hence this question. Your point is that, if one sentence is “A, B”, and the other one is “C, D”, in order to combine them into one, one just puts them together as they are and obtains “A, B, and C, D”, right?
    – Ivan
    Commented Nov 1, 2017 at 13:42
  • Yes, that is correct. Or you can use ";" instead of ", and" if you prefer. :)
    – Davo
    Commented Nov 1, 2017 at 14:38
  • Actually, now that I’ve read more carefully the ELU threads you mentioned, I’ve realized that this one answers my question and, moreover, provides two references, namely Strunk and Gregg (especially the latter). The other sources are a bit misleading. I think that ELU thread should be put front and center.
    – Ivan
    Commented Nov 1, 2017 at 18:50

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