Equality is a central principle in constitutional law yet it raises a plethora of conceptual and practical challenges for jurists, theorists, legal scholars, and political scientists. To explore the various facets of equality, the IACL held a roundtable on “The Principle of Equality: New and Old Challenges,” which was hosted by the University of Siena on June 15-16, 2023. The roundtable, which featured speakers from around the world, brought together a truly global and comparative set of perspectives on the principle of equality in constitutional law. In this report, we have summarized the major themes of the roundtable. Given the number of speakers and topics, we have not provided a separate discussion of each speaker’s contributions (with the exception of the keynote speech and the closing remarks). For further details on the papers of individual speakers, please see the roundtable’s program.