The Nile Mosaic of Palestrina, ancient Praeneste in central Italy, dating to about 100BC, is one of the earliest large mosaics which have been preserved from the classical world. Interpretation of the mosaic is disputed, suggestions ranging from the exotic decoration to a topographical picture or a religious allegory. This study argues that the mosaic depicts rituals connected with Isis and Osiris and the yearly Nile flood. The presence of these Egyptian religious scenes at Praeneste can be explained by the assimilation of Isis and Fortuna, the tutelary goddess of Praeneste, and by the interpretation of the mosaic as a symbol of divine providence. This book should be of interest to classical archaeologists, art historians, Egyptologists, classical philologists, ancient historians and students of ancient religion.