Northern Nigeria is home to the largest concentration of Muslims in sub-Saharan Africa. However, Susan M. O'Brien finds that the controversial practice of bori spirit possession often has challenged the dominant, public face of Islam. O'Brien tracks a long history of bori ritual persisting through several centuries of Islamic censure and British colonial suppression-as a healing practice, a form of entertainment, and a repository of Hausa memory. O'Brien situates bori spirit mediums as typical, rather than deviant or marginal members of the Muslim community. She documents a less orthodox application of Islam that forces new interpretations of how to be Muslim today.