Grammar Tip – Commas in a Series

BizWritingTip reader: “I have heard that it is now acceptable to place a comma before the ‘and’ in a list in a sentence. Is this something that was changed recently? Can you help me out?”

BizWritingTip response: When a sentence contains three or more items in a series, place a comma before the “and” to avoid confusion or to make a clear separation.


She is educated, experienced, and highly professional. (There are three reasons we should hire her.)

It is important that writers understand the rules for commas, dashes, and colons. (There are three separate areas writers should be clear on.)

But if the separation is clear because the reader already knows the information or the information is self evident, you do not need a comma before the “and.”


The American flag is red, white and blue. (The reader understands there are three colours here.)

The train stops at Toronto, Chatham and Windsor. (The reader knows these are three separate cities.)

I trust this BizWritingTip is timely, helpful, and easy to follow.


  • Simon Worrall

    Your guidance on the use of Oxford commas is eminently sensible, but it is worth noting (as you no doubt know) that Strunk, Follett and Chicago all mandate the use of the serial comma. This is the case even when the meaning is clear, as in the “red, white, and blue” example.

    On the other hand, the Times, AP and others decry the use of serial commas, except where the final item contains a conjunction or the list elements are complex phrases. By the way, in a somewhat self-referential question, would you have used a comma before the ‘or’ in the previous sentence?

    Where I believe the grey zone lies is in the definition of ‘complex phrase’. For example, I wouldn’t use a serial comma in the first example you gave above; ‘highly professional’ does not seem to me to be sufficiently complex to warrant separation, but I recognize that such an omission is open to debate.

    On a related note, several years ago I was doing some subcontract work for an agency and received negative feedback on my use of colons. Specifically, I had failed to use complete phrases prior to my colons, as in “The components of this assembly include:” as opposed to “The components of this assembly include the following:”. I know the first form is incorrect (as Strunk makes clear), but the second form has always seemed awkward to me. It wastes space, and I tend to run out of variants of “the following”, especially when the subject matter requires many bulleted lists. I would appreciate your thoughts on this; for me, this has always been Hobson’s choice, as there both is the guilt of using the incorrect form and the pain of reading that which is “correct”.

    After waving Strunk at me while criticizing my use of colons, the same person then berated me for using Oxford commas. I thought it impolitic to point out Strunk’s view on the subject.