This book constitutes the proceedings of the 17th Asian Symposium on Programming Languages and Systems, APLAS 2019, held in Nusa Dua, Bali, Indonesia, in December 2019. The 22 papers presented in this volume were carefully reviewed and selected from 50 submissions. They were organized in topical sections named: Invited Papers, Types, Program Analysis, Semantics, Language Design and Implementation, Concurrency, Verification, and Logic and Automata.