English mystical poet and author of such works as Mysticism (1911), The Mystic Way (1913), and Worship (1936), which helped establish mystical theology as a respectable discipline among contemporary intellectuals.

Underhill was a lifelong Anglican, but she was also attracted by Roman Catholic piety and religious experience. By 1940 she had supplemented her earlier and more diffuse mystical attitudes with a greater understanding and acceptance of institutional and sacramental elements in traditional Christianity, and she had come to centre her theology on an experience of Christ.

A frequent lecturer at conferences and seminaries, she also conducted retreats from 1924 and gained a reputation as a leading religious counselor. She was a contributor to numerous journals and was the theological editor of The Spectator from 1929 to 1932. Among her other works are Man and the Supernatural (1927), The Mystery of Sacrifice (1938), and two books of poetry, The Bar-lamb's Ballad Book (1902) and Immanence (1913).