As Dean of Berkeley, Ladd was seen as an inspiring if sometimes controversial figure. Socialist in sympathies, he chaired a major review of child welfare for the state of Connecticut. He was responsible for bringing to the USA a number of sympathetic Anglican thinkers as visiting professors including Percy Dearmer and Geoffrey Studdert Kennedy.
Ladd was active in the dissemination of Liturgical Movement principles in the Episcopal Church in the United States of America. His book Prayer Book Interleaves, published only after his death, was based on columns that had appeared in the Episcopal Church magazine The Witness. It was reprinted in 1957 with a new introduction by his student Massey H. Shepherd and then again in the centenary year of his appointment as Dean of Berkeley.
Shepherd himself and others including Urban T. Holmes III viewed Ladd as the instigator of the processes of reform that ultimately led to the adoption of the 1979 Book of Common Prayer.[6]
Armentrout, Donald S.; Slocum, Robert Boak, eds. (2000). "Ladd, William Palmer". An Episcopal Dictionary of the Church: A User-Friendly Reference for Episcopalians. New York: Church Publishing. p. 291. Retrieved August 4, 2020.
Moriarty, Michael (1995a). "Associated Parishes and the 1979 Prayer Book". Anglican and Episcopal History. 64 (2): 195–227. ISSN0896-8039. JSTOR42611697.