What’s in a Name?
Its generic name is the serial (or series) comma, but many people know it by a fancier name: Oxford comma.
The serial comma is the one before and, or, or nor at the end of a series of three or more items. It’s the comma after b in “a, b, and c”—and, incidentally, the comma after the first or in the previous sentence.
Most book publishers (and their editors) swear by it, and CMOS requires it. By clearly demarcating the last two items in a series, the serial comma adds precision.
Many journalists, on the other hand, will tell you it’s rarely necessary. The Associated Press Stylebook says to use it only in cases where its absence might lead to ambiguity. For example, in “a, b, and c and d” (where c and d form a unit), the comma after b is essential.
Whether you use it or not, you may still want to know: Why is it called the Oxford comma?
Oxford is the oldest university in the English-speaking world and has the second-oldest university press, after Cambridge. Both presses trace their founding to the sixteenth century (the University of Chicago Press, by comparison, was founded in 1890).
But the deciding factor is that Oxford University Press (like Chicago) has long published a major and influential style guide. This guide began in 1893 as a set of in-house rules for “compositors and readers” by Horace Hart. First officially published in 1904, it has been through many editions since.*
The latest successor to that original set of rules is New Hart’s Rules: The Oxford Style Guide (2nd ed., Oxford University Press, 2014). Section 4.3.5 of New Hart’s Rules, which carries the title “Serial Comma,” acknowledges the name “Oxford comma” but doesn’t claim to have a monopoly on the style:
The presence or lack of a comma before and or or in a list of three or more items is the subject of much debate. Such a comma is known as a serial comma. For a century it has been part of Oxford University Press style to retain or impose this last comma consistently, to the extent that the convention has also come to be called the Oxford comma. However, the style is also used by many other publishers, both in the UK and elsewhere.
Hart’s rulebook wasn’t always so explicit.
A Comma by Any Other Name
Early editions of Hart’s Rules didn’t mention the serial comma at all—and didn’t even specify that it must be used.
As of March 1902, for example, when the thirteenth edition of Oxford’s in-house guide was produced, the advice related to commas consisted of a mere ten lines at the beginning of a section on punctuation (p. 22):
Commas to be as a rule inserted between adjectives preceding and qualifying substantives, as—
‘an enterprising, ambitious man,’
‘a gentle, amiable, harmless creature,’
‘a cold, damp, badly lighted room.’
But where the last adjective is in closer relation to the substantive than the preceding ones, omit the comma, as—
‘a distinguished foreign author.’
Notice that not one of those examples features a serial comma.
Not that it wasn’t Oxford style to use the serial comma, as its appearance elsewhere in the guide shows—for example, in the phrase “Baptist, Christian, Nonconformist, Presbyterian, Puritan, and other denominational terms” (p. 18).
In published books, at least in English—back then as now—the serial comma was common.†
And for Hart’s limited audience of compositors and readers at Oxford UP, it went without saying.
The Birth of Oxford’s Comma
By March 1904, Hart’s Rules for Compositors and Readers, now in its fifteenth edition, had gone into publication, which meant it was offered for sale to the general public. By July of that year, it was already into its eighteenth edition—or fourth for publication.‡
The first ten lines of advice on commas in the July 1904 eighteenth edition were a verbatim replay of the advice and examples quoted above from the unpublished March 1902 thirteenth edition (see the 18th ed., p. 34). Added since then was a concluding sentence advising the use of commas to set off “such words as moreover, however, &c.” (p. 35).
But a lot happened between the summers of 1904 and 1905.
In July 1905 the nineteenth edition (fifth for publication) appeared. According to the preface, the section on punctuation had been “remodelled” for the new edition (p. 3). Among the upgrades, the comma now merited its own subsection, and—the thing we’ve all been waiting for—there was a brand-new example featuring the serial comma (p. 37; note the line space before the final example, present in the original):
Commas should, as a rule, be inserted between adjectives preceding and qualifying substantives, as—
An enterprising, ambitious man.
A gentle, amiable, harmless creature.
A cold, damp, badly lighted room.
Peter was a wise, holy, and energetic man.
A numbered footnote to that new example—“Peter was a wise, holy, and energetic man”—tells us that it’s taken from Spelling and Punctuation, by Henry Beadnell (published by Wyman in 1880, though Hart doesn’t specify the year), a source that Hart recommends in an expanded introduction to the section on punctuation.
It’s probably best, however, that this little detail is lost to history. Beadnell, who like Hart was a printer, did argue for the serial comma; his Guide to Typography (1859) includes a thorough defense of it (see pt. 1, rule 5, on pp. 119–20; see also rule 7 on pp. 120–22, in which the “wise, holy, and energetic” example makes an early appearance, at the top of p. 121). But Beadnell comma doesn’t have the same ring to it as Oxford comma.
So, mark your historical calendars: July 1905, birth of the Oxford comma.
Chicago, the Second City
Meanwhile, in the 1890s, the University of Chicago Press had been busy devising its own set of in-house rules—along the same timeline as Oxford’s but an ocean and half a continent away.
As at Oxford, what started as a stylesheet soon grew into a book, today known as (you guessed it) The Chicago Manual of Style, now in its seventeenth edition.
The very first edition of the Manual, published in 1906, included a seven-and-a-half-page section on the comma (Hart’s 1905 edition covered the subject in a page and a half).
The serial comma was the subject of paragraph 130 (pp. 46–47), which opened as follows:
Put a comma before “and,” “or,” and “nor” connecting the last two links in a sentence of three or more. . . .
Tom, Dick, and Harry; either copper, silver, or gold
More than a hundred years later, it’s still the rule.
Chicago in 1906 was famous as the second largest city in the United States, yet it was home to what was then a mere fledgling institution and university press. And it was a year too late to claim the name.
* The closest Cambridge equivalent to Hart’s guide is the excellent Copy-Editing: The Cambridge Handbook, by Judith Butcher, first published in 1975.
† You’ll find a serial comma on the opening page of the 1611 first edition of the King James Bible, in “Grace, Mercie, and Peace.” The serial comma is also evident in many novels of the era, from Henry Fielding’s Tom Jones (1749) to Jane Austen’s Pride and Prejudice (1813) and George Eliot’s Middlemarch (1871–72).
‡ Hart’s Rules went through four editions in 1904, two in April alone; printers worked fast in those days—though these early editions were relatively small: the eighteenth came in at under eighty pages; the nineteenth would add ten more.
Editor’s Corner posts at Shop Talk reflect the opinions of its authors and not necessarily those of The Chicago Manual of Style or the University of Chicago Press.
~ ~ ~
Russell Harper (@cpyeditor) is editor of The Chicago Manual of Style Online Q&A and was the principal reviser of the last two editions of The Chicago Manual of Style. He also contributed to the revisions of the last two editions of Kate L. Turabian’s A Manual for Writers of Research Papers, Theses, and Dissertations.
The Chicago Manual of Style, 17th edition
Please see our commenting policy.