The serial or Oxford comma

November 29, 2011

Chris asked me to write something about the serial comma (also known as the Oxford comma, among other names). Thanks for the suggestion, Chris!

Bottom line: Separate the last two items in a list with a comma if they could be misinterpreted as being a single item.

A serial comma is the final comma in a run-on list of items; it goes before the ‘and’. (A run-on list is contained within the sentence – it’s not a bulleted list.)

In this phrase, the serial comma is the one immediately after ‘selecting’:

‘…identifying, screening, qualifying, selecting, and integrating the appropriate new technologies to be used in the project’.

Whether you use a serial comma in your writing or not mostly depends on where you went to school. If you went to school in the US, there’s a very good chance that you always use it. However, if you went to school in Australia or Great Britain, you may not use it at all, or only sometimes.

Various style guides have differing rules for its use, so it can all get a little confusing. The Australian Style Manual says this about commas in run-on lists:

‘Commas are used to separate items in a simple series or list within a sentence (e.g. The details required are name, date of birth, address and telephone number.) Sometimes a comma is needed between the last two items to ensure clarity (e.g. They should seek the support of landholders, philanthropists, government, and community and industry groups.)’

Despite being raised in the Australian education system, I tend to add a serial comma after the second last item in most run-on lists to avoid any possibility of ambiguity.

Let’s look at a simple example:

Her favourite pies were lemon meringue, mulberry, apple and pecan.

Without the serial comma, ‘apple and pecan’ could be interpreted as a pie containing both apples and pecans. If the writer meant that apple and pecan were two different types of pie, then they should have added a comma after ‘apple’ to remove any possibility that ‘apple and pecan’ could be interpreted as the one pie:

Her favourite pies were lemon meringue, mulberry, apple, and pecan.

That single comma after ‘apple’ removes all ambiguity and makes it clear that she likes four different types of pie, not three.

Other resources:

[Links last checked November 2011; based on a Writing Tip I wrote for my work colleagues]


  1. My favourite example of an unfortunate lack of a serial comma is the book dedication quoted (made up?) by Teresa Nielsen Hayden: “To my parents, Ayn Rand and God.”

  2. In addition, of course, that renowned version: eats shoots and leaves

  3. […] The serial or Oxford comma (cybertext.wordpress.com) […]

  4. […] written before about commas before (see the information on serial/Oxford commas in lists: https://cybertext.wordpress.com/2011/11/29/the-serial-or-oxford-comma/), so this time I’ll use some light-hearted examples found on the internet about how commas and […]

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