He published the New England Primer, the first textbook in British America, and edited the first multi-page newspaper there, Publick Occurrences Both Foreign and Domestick, from 25 September 1690.
He published the pamphlet Appeal from the Country to the City in 1679 by Charles Blount, opposing the succession of James, Duke of York, and was consequently convicted of sedition and ordered to pay a fine he could not afford.
He moved to Boston in 1686 to start the London Coffee House, which provided both men and women (unusually at the time) access to foreign newspapers and books.
It focused on local news, and included gossip; one item concerned King William's War and atrocities attributed to Native American forces allied to the British, current in September 1690.
Harris was also active in community service, supporting homeless shelters and orphanages.