Comparing the growth and potential for further development of the Bahá'í Faith and Wicca in Britain, this study uses the "theory of relevance" developed by Dan Sperber and Deidre Wilson to explain cognition in the field of linguistics and applied to the field of religious studies by the author in an earlier work. Outlining the milieu in which both traditions began and noting possible overlaps of individuals and networks, it continues by contrasting motifs of beliefs and values between the two systems and investigates the history of both by arguing that relevance is the driving force in their respective development. Thus, the Bahá'í Faith, which began by attracting radical and progressive elements, gradually became more conservative as its principles became generally accepted and its legalistic structure ensured the upholding of traditional concepts of family and sexuality. Conversely, the interaction with feminism and the ecology movement caused Wiccans to embrace a radical and inclusive perspective that was not present at the inception of the Gardnerian tradition. Finally, the potential for growth and influence of both traditions is assessed within the context of the theory of relevance.