This book constitutes the proceedings of the 34th International Conference on Parallel and Distributed Computing, Euro-Par 2023, held in Limassol, Cyprus, in August/September 2023. The 49 full papers presented in this volume were carefully reviewed and selected from 164 submissions. They are covering the following topics: programming, compilers and performance; scheduling, resource management, cloud, edge computing, and workflows; architectures and accelerators; data analytics, AI, and computational science; theory and algorithms; multidisciplinary, and domain-specific and applied parallel and distributed computing.