This chapter presents the mythical accounts located in Sicily that appear in the Historical Library , as well as the Sicilian cults and sanctuaries mentioned by Diodorus. On the basis of this diverse material, it examines the function of sanctuaries in the historical account and the role of religious data in the construction of Diodorus’ narrative, in order to identify the issues at stake in Diodorus’ presentation of Sicilian myths and cults. Beyond a patriotic emphasis on Sicilian cultural resources, beyond a pedagogical aim that exalts the piety of the great leaders and benefactors, religious data are involved in building an image of Sicily as the geographical and cultural centre of a unified Mediterranean world.