This edited volume presents research pursued within the PRIN-2022 project Mediterranean Multipolarity and Roman Unipolarity: Power Competition and Collaboration in the Graeco-Roman Geopolitics (3rd–2nd century BCE). The contributions first investigate how the upheavals of the Pyrrhic War affected the relations of the Greek communities of southern Italy with Rome. They also explore how the new political situation in the peninsula was translated on the level of historiographical writing, which intensified in the 3rd century and counted Timaeus of Tauromenium among its most important exponents. The following contributions pay due attention to episodes of coercive mobility in Italy after the war. They also demonstrate that the war influenced the construction of identities, primarily civic and ethnic ones, as can be traced through literary and archaeological evidence. The final contributions examine how the memory of Pyrrhus was exploited in the Roman political discourse of the Late Republic. To this end, the most relevant passages from Greek and Roman authors such as Polybius and Cicero are considered, which may interest scholars and students from various fields of Classical studies.