This book constitutes the refereed proceedings of the Third Asian Symposium on Programming Languages and Systems, APLAS 2005, held in Tsukuba, Japan in November 2005.

The 24 revised full papers presented together with 3 invited talks were carefully reviewed and selected from 78 submissions. Among the topics covered are semantics, type theory, program transformation, static analysis, verification, programming calculi, functional programming languages, language based security, real-time systems, embedded systems, formal systems design, Java objects, program analysis and optimization.