The Ptolemaic and Seleucid empires are usually studied separately, or otherwise included in broader examinations of the Hellenistic World. This book proposes a more dynamic comparison, with a particular, though not exclusive focus on the interaction of the royal centers with local populations and elites. Both political entities are approached as multiethnic empires whose resemblance and entanglement are sufficient to make comparisons meaningful. In the process of comparing them, differences and connections become more salient and better explained. We aim to explore the different structural capacities for, and levels of, integration that were either aspired to or achieved by the kings and populations of each empire.