Crookes joined the Society for Psychical Research, becoming its president in the 1890s: he also joined the Theosophical Society and The Ghost Club, of which he was president from 1907 to 1912.
Crookes uniuse á Sociedade para a Investigación Psíquica, converténdose no seu presidente na década de 1890: tamén se uniu á Sociedade Teosófica e ao Ghost Club, do que foi presidente de 1907 a 1912.