Defining, Understanding, and Embracing the Serial Comma The serial comma, also known as the Oxford comma or the Harvard comma (because the Oxford and Harvard University Press style guides require it), is the final comma before the coordinating conjunction "and" in a list of three or more items. While many presses in addition to Oxford and Harvard favor the serial comma, newspapers have historically omitted it to save space on the printed page. Reflecting this journalistic preference, our own Office of Communications recommends its omission in the case of "print and electronic materials written for and about Princeton University" unless "it [...]