This book constitutes the refereed proceedings of the 4th International Symposium on Practical Aspects of Declarative Languages, PADL 2002, held in Portland, OR, USA in January 2002. The 18 revised full papers presented together with three invited contributions were carefully reviewed and selected from 37 submissions. Among the topics addressed are objects, ACL, higher order logic programming, compilers, embedded programs, types, XML parsing, texture generation, logic programming, generic programming, modeling languages, Prolog programming, garbage collection, etc.