Bornat Belfast, Ulster, after taking his degree at the University of Cambridge, Reid settled down in Belfast, where he spent most of his life. Reid's writing centre on the world of boys, and are permeated by the quest for the ideal playmate friend. The celebration of a Greek ideal of male friendship in his works placed Reid's characters in a pagan, lyrical world. He died at Warrenpoint, County Down.

His romantic and mystical novels includes The Kingdon of Twilight (1904), The Garden God: a Tale of Two Boys (1905), Following Darkness (1913), and a trilogy published with the title Tom Barber: Uncle Stephen (1931), The Retreat (1934), and Young Tom (1944).

Reid's dominant subject is boyhood and adolescence. He also wrote two autobiographies, Apostate (1926), and Private Road (1940).