This book constitutes the refereed proceedings of the First Asian Symposium on Programming Languages and Systems, APLAS 2003, held in Beijing, China in November 2003.The 24 revised full papers presented together with abstracts of 3 invited talks were carefully reviewed and selected from 75 submissions. The papers are devoted to concurrency and parallelism, language implementation and optimization, mobile computation and security, program analysis and verification, program transformation and calculation, programming paradigms and language design, programming techniques and applications, program semantics, categorical and logical foundations, tools and environments, type theory and type systems.