Interested in a variety of subjects, he devoted himself chiefly to the philosophy of religion, and published The Science of Thought (Boston, 1869; revised 1891). He also wrote:
Fichte's Science of Knowledge (1884)
Poetry, Comedy and Duty (1888)
Religions before Christianity (1883)
Ethics for Young People (1891)
The Gospel of Paul (1892)
Everett had suggested, before his death in Cambridge in 1900, that the Harvard Divinity School publish a non-denominational theological journal. A few years later, his daughter's will provided the first bequest which led to the publication in 1908 of the first issue of the Harvard Theological Review.