William Strunk's Rules of Usage states:

If a dependent clause, or an introductory phrase requiring to be set off by a comma, precedes the second independent clause, no comma is needed after the conjunction.

Strunk's example illustrates the point:

The situation is perilous, but if we are prepared to act promptly, there is still one chance of escape.

However, I would be tempted to put a comma after the "but," like this:

The situation is perilous, but, if we are prepared to act promptly, there is still one chance of escape.

So, I know you're thinking, "Well, Strunk's Rules of Usage says that you're wrong. No comma."

But is Rules of Usage really the best source? I'd like to see this rule in a more contemporary and authoritative source, like the Chicago Manual of Style.

There are many instances — such as in The New York Times — where the comma is included before a parenthetical comment that comes after a coordinating conjunction.

Any authoritative source on the issue?

  • 2
    Nitpick: it is William STRUNK, not STUNK. Commented Feb 3, 2011 at 20:32
  • Strunk and White are an authoritative source. You refer to the following structure [independent clause 1] , [conjunction] (,) [dependent clause to independent clause 2] , [independent clause 2] . The [dependent clause to independent clause 2] element (the if-clause in your example) is not parenthetical. (Well, in most cases, anyway.) Dependent clauses and parenthetical elements should not be piled up into the same rule.
    – Bernadette
    Commented Jun 23, 2016 at 4:38
  • 1
    @Bernadette: I have never seen or used S&W, but I hear lots of people being highly critical of them...Fowler's, on the other hand, is at least widely respected, even by his opponents. Commented Jun 23, 2016 at 21:01

7 Answers 7


Ordinarily parenthesis should be marked with commas on both sides. But Fowler recommends that the first comma should be left out after a coordinating conjunction if what follows is a simple adverbial phrase—if I interpret him correctly. (Coordinating conjunctions are and, or, but, and possibly some semi-conjunctive adverbs like so, therefore, however, etc.) The comma should be retained before a subordinate clause or when its omission would cause ambiguity. This probably includes conjunctions that are not at the beginning of a sentence. Fowler's advice seems balanced and practical.

  • Cleopatra appeared poised and composed. But on the inside, she was seething with rage. — Simple adverbial phrase at the beginning of a sentence.

  • Her only option was to support Mark Anthony once again. But, if he should perish, it would be the end of her. — Not a simple adverbial phrase but a clause.

  • She knew her cause was lost and, in a fit of final despair, had a serpent brought in to extinguish her life with its venom. — Not at the beginning of a sentence.

The relevant text from Fowler's The King's English follows. He is arguing for general laxity with adverbial phrases, and would generally allow both commas and no commas around them. He goes on to say that, if commas are used, one must never omit one but write the other; however, he gives the above rule as an exception, in order to avoid an abundance of commas, logical though they might be.

Laxity once introduced, however, has to be carefully kept within bounds. It may be first laid down absolutely that when an adverbial clause is to be stopped, but incompletely stopped, the omitted stop must always be the one at the beginning, and never the one at the end. Transgression of this is quite intolerable; we shall give several instances at the end of the section to impress the fact. But it is also true that even the omission of the beginning comma looks more and more slovenly the further we get from the type of our above cited sentence. The quotations immediately following are arranged from the less to the more slovenly.

  • His health gave way, and at the age of fifty-six, he died prematurely in harness at Quetta.—Times.

  • If mankind was in the condition of believing nothing, and without a bias in any particular direction, was merely on the look-out for some legitimate creed, it would not, I conceive, be possible...—Balfour.

  • The party then, consisted of a man and his wife, of his mother-in-law and his sister.—F. M. Crawford.

  • These men in their honorary capacity, already have sufficient work to perform.—Guernsey Evening Press.

It will be observed that in the sentence from Mr. Balfour the chief objection to omitting the comma between and and without is that we are taken off on a false scent, it being natural at first to suppose that we are to supply was again; this can only happen when we are in the middle of a sentence, and not at the beginning as in the pattern Cranmer sentence.

  • Both the OP and Strunk and White refer to the following structure [independent clause 1] , [conjunction] (,) [dependent clause to independent clause 2] , [independent clause 2] . This is a complex compound sentence. Not all your examples are complex compound or even compound. The [dependent clause to independent clause 2] element is not parenthetical. Well, in most cases, anyway. Dependent clauses and parenthetical elements should not be piled up into the same rule.
    – Bernadette
    Commented Jun 22, 2016 at 23:53
  • @OksanaDashwood: Why should all of my examples be compound sentences? I was laying out a general rule, covering several different types of sentences, including that in the OP. As to that if clause, why is it not parenthetical? It is parenthetical according to Fowler and me if the author wants to separate it from its main clause with a comma, and it should therefore be marked by commas on both sides. Commented Jun 22, 2016 at 23:59
  • This comment went into the wrong place, sorry about the confusion. But. Parenthetical elements can be removed from the sentence without affecting the meaning, and so, if-clauses are rarely parenthetical. They are usually dependent clauses that are (more often than not) essential. Moved to the front of a main (independent) clause, they become introductory clauses, but not parenthetical. If you can't set it off in parentheses, using dashes, or remove it altogether, it's not parenthetic.
    – Bernadette
    Commented Jun 23, 2016 at 8:13
  • @Bernadette: But why can't you remove the if clause from the OP? I'd say they can usually be removed. When they aren't separated from the main clause by one or two commas, then they may be non-parenthetical; but, then they are, they are. Commented Jun 23, 2016 at 12:03
  • You can remove it, but it alters the meaning of the sentence.
    – Bernadette
    Commented Jun 23, 2016 at 13:11

I don't have a membership to the CMS, so I can't speak to their take on it. But I would say that the meaning, or at least the tone that you're trying to communicate it subtly different between the two phrases. In your punctuation, the speaker is expressing doubt that "we are prepared to act promptly", and perhaps expressing the subjunctive as a bit of an aside.

And if the actual meaning is different, then rules of usage be damned. I personally would punctuate it thusly:

The situation is perilous; but - if we are prepared to act promptly - there is still one chance of escape.

No commas at all.

  • Well, that's not my sentence, just the example from Rules of Usage. I was looking more for a generic guideline — someone was trying to tell me that a comma after the conjunction is just plain wrong. In any case — and for what it's worth — I do like your version of the sentence. Commented Feb 3, 2011 at 22:04
  • Yes, no commas at all but a different tone altogether.
    – Bernadette
    Commented Jun 23, 2016 at 8:34

"Well, Stunk's Rules of Usage says that you're wrong. No comma."

"no comma is needed" does not mean "it is wrong to use a comma."

  • Hmm, good point. This arose from a debate where the other side was arguing that it was just plain wrong. The CMS has a really great Q&A Page, and I really like the way they answer a lot of questions, like this one. People come in with a lot of nit-picky questions, and they always seem to respond along the lines of "do whatever makes the most sense." I like that approach. Commented Feb 3, 2011 at 21:59
  • I do too. Writing is about communication. The point is to be as clear as possible.
    – horatio
    Commented Feb 3, 2011 at 22:06
  • Yes, it does mean that. It's not just Strunk and White but many other sources that agree that it is indeed wrong to use a comma after a coordinating conjunction. And the lack of it does not usually bear any impact on the clarity. It would be very unusual to use such commas, and if you have a case where the are required for clarity, you should consider recasting the sentence in the first place.
    – Bernadette
    Commented Jun 22, 2016 at 23:43

I was once an editor of a law review journal. I did not find Strunk helpful as to this issue. Generally, I would insert a comma after the conjunction but, for the sake of clarity, I would not place a comma before the conjunction. My wife, an English major and also a lawyer, however, disagrees with me. Of all of the grammar issues we have ever discussed, this is the only issue upon which we disagree.

  • 2
    I don't have a lot of time for style guides anyway, and as I understand it, Strunk is better-known as a target of criticism than as a serious contender for the misguided concept of "absolute authority". But on the principle that "less is more", and also in line with the modern trend towards using less commas overall, they're quite correct to say that first comma is unnecessary. And like you, I would discard it. It adds nothing to legibility, and the sheer preponderance of commas is just pointlessly distracting. AND you wouldn't pause in speech! Commented Sep 9, 2012 at 21:43
  • There always must be a comma before a conjunction separating two independent clauses.
    – Bernadette
    Commented Jun 22, 2016 at 23:25
  • Some Strunk and White's guidelines are just that, guidelines, but some are actually rules that are echoed around the writing world. E. g. this is ungrammatical whichever way you look at it: "I would insert a comma after the conjunction but, for the sake of clarity, I would not place a comma before the conjunction." Your wrote two independent clauses joined with a coordinating conjunction with no comma before it. Only in rare cases can you get away without a comma before such a conjunction, and yours is not such a case. What you did is called a run-on sentence and is a common grammatical error.
    – Bernadette
    Commented Jun 23, 2016 at 8:33
  • @Bernadette The Writing Center at The University of Wisconsin - Madison: The Writer's Handbook is not so prescriptive (as your first comment): 'When a coordinating conjunction joins two independent clauses, a comma is used before the coordinating conjunction (unless the two independent clauses are very short).' Grammar.ccc.comm gives what I consider to be the best sitrep and advice: ... Commented Oct 13, 2016 at 15:55
  • 'When a coordinating conjunction connects two independent clauses, it is often (but not always) accompanied by a comma: 'Ulysses wants to play for UConn, but he has had trouble meeting the academic requirements.' When the two independent clauses connected by a coordinating conjunction are nicely balanced or brief, many writers will omit the comma: 'Ulysses has a great jump shot but he isn't quick on his feet.' Commented Oct 13, 2016 at 15:56

Well my wife just showed me the new Chicago Manuel of Style. According to provisions 6.28 and 6.32, I lose the argument. As always, she wins. Do not insert a comma after a conjunction, but according to the Chicago Manuel of Style, you should insert a comma before the conjunction.

  • 1
    I don't know if you can't post comments because you don't have sufficient reputation points, but the moderators won't like you posting comments as answers. I'm actually going to vote to close this question now it's come to my attention (pointless and subjective, imho). But please stick around, and post some answers that can get upvoted, so you'll be able to post real comments! Commented Sep 9, 2012 at 21:49
  • Does your wife know about Manuel? Commented Oct 13, 2016 at 16:02
  • CMoS gives advice not diktats on such matters (although in an arrogating manner). Other style guides are less prescriptivist. Commented Dec 26, 2020 at 19:26

This is to address the parenthetic argument and to show that not all dependent clauses starting with subordinating conjunction are parenthetic. My previous answer explains why whether it's parenthetic or not has nothing to do with the punctuation question such as the OP's.

Let's reverse the order by putting the dependent clause after the main add it's commonplace to do. The punctuation guidelines for dependent clause following its main clause is no comma before the subordinating conjunction - unless the dependent clause is parenthetical, which it rarely is.


A. Non-parenthetic (The if-clause cannot be removed without altering the meaning of the sentence. It provides essential information.) The event can go ahead if the rainclouds keep away.


B. Parenthetic (The if-clause can be removed, placed in parentheses, or set of with dashes -depending on author's intent - because it provides additional information.) The event can go ahead on a dry day, if the rainclouds keep away.

And so on:

A. Leanne treated him as a criminal deserved to be treated. vs. B. Leanne treated him with a shadow of contempt, as a criminal deserved to be treated.

A. He divorced before he went to jail. vs. B. He divorced in 1996, before he went to jail.

A. She said she would take on the project if she was given enough time. vs. B. She said she would take on the project with a reasonable deadline, if she was given enough time.

Parenthetic clauses starting with subordinating conjunctions (B) are always separated by a comma from their main clause, despite the general sweeping guidelines of not putting a comma before a subordinating conjunction which follows a main clause. (Try removing commas from Bs, and the meaning changes or becomes confusing.) Also, as Bs are parentheticals that clarify or add to what immediately precedes them, you cannot move them out to the front of the sentence without rendering the sentence ridiculous. (I am not even sure if you could call these Bs dependent clauses.) But if something can be moved to the front, it does not mean it's non-parenthetic, and some sentences don't suffer when a parenthetic clause starting with a subordinating conjunction is moved to the beginning. (Try doing it with these: "He finally went to jail, after 10 years on the run" or "He would drag himself home at dawn, if he could still walk by that time." Parenthetical? Yes. Can be moved to the front of the sentence? Yes.) The parenthetical can be moved to the front without much affecting the meaning. But all the B examples above contain dependent elements that are parenthetic: they are all extra information, clarification, or afterthought. All of the As give information you cannot derive anywhere else in the sentence or that which is essential to the nature of the notion being expressed. That's the difference.

The OP's example (which is from Strunk and White) indicates that the one chance of success exists only if prompt action is considered. And really this one can be either. Sometime it's difficult to decide whether an expression is parenthetic or essential, and when punctuating such cases, an author would go with what his intended meaning is and punctuate appropriately - putting a comma before the subordinating conjunction that follows the main clause, as in Bs above.

In most of the As, though, the dependent non-parenthetic clauses can be moved to the front of the sentence, and such a transposition would let the sentence retain the meaning while giving a different tone to what is being said. However, transposition does not make any of these dependent clauses parenthetic, but merely introductory: without them the sentences do not at all say the same thing, and most of the examples provided don't even make sense.

So a clause starting with a subordinating conjunction, transposed to the beginning of the sentence can be parenthetic / non-essential (or defining in case of relative conjunctions) or essential (or non-defining in case of relative conjunctions). But if we go back to the OP's question, the of-clause being parenthetic or essential such as so:

He was convicted, and before he went to jail, he divorced. (Could be argued essential or non essential depending on context which is missing.) She maintained that she rejected the task because of its unreasonable deadline, but if she was given enough time, she said she would take on the project. (Essential.) The fair will be outdoors, and if the rainclouds keep away, it will go ahead. (Essential.)

But the parenthetical argument doesn't change anything for the point at hand (punctuating a coordinating conjunction preceeding such a clause), because that first comma still goes BEFORE the coordinating conjunction and never after it, unless clarity is at stake - then both commas are included in complex compound sentences where two independent clauses are joined by a coordinating conjunction. But the same is true whether the comma before the joining coordinating conjunction would be grammatical (compound sentence where the conjunction separates two independent clauses) or not (two-part compound predicate or compound object or two-item list) without the introductory clause. But of course, the OP's question seemed to refer to cases as the first one:

[main clause 1] , [coordinating conjunction] ( comma or no comma?) [subordinating conjunction] [dependent or parenthetical poor introductory element for m. clause 2] , [main clause 2]

And I pointed out that some examples didn't match the pattern because, of course, a question of putting a comma before a coordinating conjunction preceding an introductory clause, parenthetic or not, usually arises only where complex or complex compound sentence is discussed. There is a trend of moving the first comma to after the coordinating conjunction on grounds of parenthesis, so here I point out that parenthesis had nothing to do with it, and whether parenthesis or not, the rule is the same: no comma after And or But.

(Please forgive any typos or autocorrect errors. This is put together on a tablet.)


------ Strunk and White - rule 4

In their rule 4, Strunk and White (and I believe the OP's question too) refer to complex compound structures only, and only those that follow pattern such as this:

[independent clause 1] , [conjunction] (,) [dependent clause to independent clause 2 - introductory clause] , [independent clause 2] .

As do many other authoritative source, Strunk and White state that the second comma (the one in parentheses) should not be used. And for a good reason, too.

Not every pair of commas indicates that the element they surround is non-essential to the sentence or parenthetic. The first comma in the example above separates two independent clauses, and the second one indicates the boundary of a dependent clause that precedes its main (independent) clause. The rule that governs these commas is rule 4: "Place a comma before and or but introducing an independent clause" (the first comma in the example). The commas Strunk and White discuss in this rule are not parenthetic commas (and there are very few dependent clauses that are parenthetic, anyway). However, this advice is valid, widely followed, and is equally correct for parenthetic elements too (as I'll explain below). It is very rare indeed that you'd have a comma immediately following a coordinating conjunction such as and or but.

This rule is for complex compound sentences such as outlined above, where two independent clauses are joined by a coordinating conjunctions "and" or "but" (and a few other conjunctions that are outlined later on in the rule) and where the conjunction is followed by a dependent clause, or an introductory phrase requiring to be set off by a comma, which precedes the second independent clause.

Unlike some answers here suggest, adverbs are a different case altogether.

------ Strunk and White - rule 3

This rule refers to any parenthetic expressions that need to be set off by commas, when a conjunction precedes the parenthetic expression. (Not every parenthetic expression needs to be set off by commas or set off all.) The rule applies to constructions such as but not limited to:

[Subject] [predicate 1] , [coordinating conjunction] (comma here would not be grammatically correct) [parenthetic expression] , [predicate 2] .


She said her farewells, and despite the earlier disagreement, gave me a hug. (Matches the pattern Strunk and White use as an example.) or He would stay for the main course, and if it would please his mother, dessert. (The pattern here is different, but the same rule still applies.)

If it were not for the parenthetic expressions, the commas before the conjunction in the examples above would constitute a grammatical blunder (except when required for clarity, which in those examples they are not) because in the first sentence it'd split a compound predicate, and in the second, compound object. And yet according to the rule, when an expression is parenthetic, making it look like one (with commas on each end) should be so low on the priority list that even the compound predicate and compound object can be made to adjust split, just as long as we avoid a comma after the conjunction - avoiding a comma after the conjunction is THAT important.

So, even when the expression is parenthetic (i.e. not essential to the meaning of the sentence), if the commas are necessary to set it off, the commas don't actually need to look parenthetic - the conjunction is also enclosed within the commas: the commas are for clarity and not to tell the reader to skip what's between them if the reader feels so inclined. No-one who reads anything such as examples above pauses to think: "Hang on! Surely if I remove what's between the commas the sentence won't make sense!" When I read such sentences, the first of the commas goes unnoticed altogether, and the second one is where a natural pause would be, and if it aids clarity, the second comma is very helpful.

A writer may suggest that not every expression following a conjunction is parenthetic (or non-essential), and some could be essential to the meaning of the sentence. When you need to set off an essential expression with a pair of commas, I would argue that the same rule still applies. If we're not concerned with making parenthetic expressions look as such, why would we do that to non-parenthetic ones?


  1. He always brought me dinner (,) and on Sundays (,) stayed to cook it himself.
  2. He worked every day (,) and if necessary (,) stayed the night too.
  3. The children played noisily (,) and when asked to stop (,) didn't pay any attention to any such requests.
  4. He always moved around the office at a leisurely pace, and only when his phone sounded that special ringtone, ran towards his desk.

The "on Sundays," "if necessary," and "when asked to stop" phrases are all essential to the meaning of the sentences 1-3, as is the clause "when his phone sounded that special ringtone" to sentence 4. Not all introductory elements need to be set of by commas, and I don't see any clarity problems problem with examples 1-3 not using any commas at all (though there may be reasons other than clarity to add them), but the example 4 definitely needs something that would help the reader.

If a non-parenthetic introductory element that needs to be set off by commas follows a conjunction, it's logical to assume that the same rule applies because, if we're not concerned about making a parenthetic expression look like one, then making a non-parenthetic expression look like a parenthetic element is just illogical, if not downright bonkers. But do we need the first comma, before the conjunction or do we only need the second comma? Yes, we need both: try the sentences with the second comma only, and you'll quickly see why you need the first one too.

How will the reader tell the difference better what's essential and what's not in the sentence? I think the reader is smarter than we may assume, and I don't think we need to worry about him misunderstanding the meaning. If there's a risk of misunderstanding, I think the problem is with the composition or the sentence structure.

------ Comma After Conjunction which Begins a Sentence and is Followed by an Introductory Expression

This is a very sparsely covered subject. Most sources will state that only in very rare cases a comma after conjunction and before the introductory expression is needed, but where exactly - no-one seems to be sure.

Everywhere says that such a comma is only justifiable in very rare cases. In my writing, I very rarely feel that a comma is necessary after a sentence-beginning conjunction and before the introductory expression that follows it. Most of the time, I don't see that such a comma adds anything to the clarity or alters the meaning of the sentence at all. I searched and searched for guidance on this, and this is the only source that I could find that makes any sense: "Include commas after coordinating conjunctions that start sentences only when a nonessential phrase or a parenthetical follows the conjunction." (Introduce Me with a Comma by Beth Hill, August 2015) I can see why the two examples provided by the blog author call for such a comma.

"Or, she wanted to know, had I left my husband?

"Yet, and this is crucial, I’d forgotten to pack my pistol."

The author says it's "a nonessential phrase or a parenthetical", but there's also clarity: remove the first comma, and the reader may need to go over the sentence more than once to understand what you're trying to say.

At the moment, unless clarity is at stake I choose to never put a comma after a sentence-starting conjunction followed by an introductory or a parenthetical expression. In my reading of novels by authors whom I love and trust, I have not seen such commas at all. (But I will continue looking.)

------ The Impression I Get

From what I see in editors' blogs and style guides, the general consensus seems to be that a comma after a conjunction makes for inelegant writing and is spurious. Some say that such commas were acceptable before but are now viewed as pedantic. I read somewhere that, although such practice was religiously adhered to many years ago and by many classical writers too, in current climate of trend toward minimal punctuation it makes for a clumsy-looking sentences, mashed your reader stumble over too many commas that don't add anything, and makes the writer look ignorant. And I agree. And just go over Lynne Truss's "Eats Shoots and Leaves" or Caroline Taggard's "My Grammar and I (Or Should That Be 'Me'?)" or Steven King's "On Writing" - anybody who's anybody in writing echoes or quotes Strunk and White. And I don't think that any of us here are in a position where to dispute Strunk and White, CMS, Fowler etc.

  • The Internet is, of course, overflowing with commas after "and," "but," "or," and The Times could contain an odd one here and there, but I just did a search in my Kindle's books - literature by respected, acclaimed authors, published within the last decade or so - and not one of them had a comma between a coordinating conjunction and an introductory (such as a dependent clause preceding its main clause) or parenthetical element (such as "of course" or noun clause etc.) following the conjunction. Not one. And I think that says something: don't do it.
    – Bernadette
    Commented Jun 23, 2016 at 9:02

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