Volume XXXI of The Italian Yearbook of International Law opens with a Symposium on the Mediterranean Sea and international law. The Symposium addresses: i) maritime delimitations; ii) the Italian law authorizing the creation of an Exclusive Economic Zone; iii) the rules governing waters off disputed territories; iv) the protection of underwater cultural heritage; v) maritime security; vi) issues of jurisdiction; vii) the conservation of biodiversity and the sustainable management of fisheries resources; viii) the Union for the Mediterranean. The Volume further contains an article on the role of cities in the evolution of international humanitarian law, and timely contributions on the Treaty of Quirinale between Italy and France; Italy’s implementation of the Statute of the International Criminal Court; State immunity in case of delegation of public powers to private actors; the Italian law against investments in anti-personnel mines and cluster munitions; Italy’s legislation adopted in the context of the COVID-19 pandemic. As in every volume the following sections cover the Practice of International Courts and Tribunals and Italian Practice Relating to International Law. The remaining part of the Volume contains a bibliographical index of Italian contributions to international law scholarship published in 2021, a book review section, and an analytical index for easy consultation and reference to materials cited in the Yearbook. Published with the contribution of ENI and Tenaris.