The comparatively historical analysis of rapidly expanding growth of Islam into Nandi Districts, away from the Islamized Kenya coastal region, against the background of the indigenous Nandi belief system and Christianity, formed the premise of this research book. The interactions of these religions have been examined in terms of mutual influences and contradictions, which impacted Islamization in Nandi society, using theoretical frameworks drawn from functionalist, diffusianist and modernization theories. The research findings contribute greatly to the corpus of knowledge in comparative religion, theology and history of the Nandi.