​The two-volume set LNCS 14771 and 14772 constitutes the refereed proceedings of the 15th International Workshop, PQCrypto 2024, held in Oxford, UK, during June 12–14, 2024.The 28 full papers included in these proceedings were carefully reviewed and selected from 76 submissions. They were organized in topical sections as follows:Part I: Applications and protocols; code-based cryptography; group-action-based cryptography; lattice-based cryptography; Part II: Isogeny-Based cryptgraphy; multivariate cryptography; quantum algorithms; transforms and proofs.