J. Leybourne Popham became a member of the Rhodesia Scientific Association in 1899, the year of its formation. He served on the association's council for 1906/7, and was joint vice-president for 1907/8. In February 1904 he delivered "Notes on the N'Natali ruins" at a meeting of the association. The paper was published in the Proceedings (Vol. 4, pp. 67-70). In 1918 he was still a member, though he resided in London by 1914 and was on active service during World War I (1914-1918).
Popham became a member of the Geological Society of South Africa in 1906 and was still a member in 1914.