He is noted for his involvement in the American Arts and Crafts movement, and as the founder of the School of Architecture at Harvard University.

His father was Samuel Mills Warren, of colonial New England ancestry, and his mother was Sarah Anne Broadfield from Shropshire.

[8] In a memoir written after Warren's death, John Taylor Boyd, one of his students, wrote: "In his teaching, the experience of a practicing architect made real and mellowed the research of the scholar.

[1] A major exhibition devoted to handicrafts was held in Boston in April 1897, inspired by the English Arts and Crafts movement.

Under Warren's leadership the American Society would reject the socialism that was an important part of the English movement.

An important part of the Society's activities was encouraging close relations between architects and designers on the one hand and craftsmen on the other.

[5]: 84–101 Warren was also involved in broader political and social issues, in particular the movement in support of the Allied cause in the years of U.S. neutrality in World War I.

He wrote: "like our language, our literature, and our common law, our political and social thought, our whole spiritual and intellectual atmosphere are by inheritance and tradition fundamentally English."

[2][3] Warren's funeral was held 7 July 1917 at Harvard's Appleton Chapel with Richard Clipston Sturgis, Morton Prince, and Charles Wilson Killam as pallbearers.

Examples include the Page House in Boston, and the competition design (not implemented) for the Cathedral of St. John the Divine in New York City.