This book constitutes the refereed proceedings of the Second International Workshop on Practical Aspects of Declarative Languages, PADL 2000, held in Boston, MA, USA in January 2000. The 21 revised full papers presented were carefully reviewed and selected from a total of 36 submissions. The papers are organized in topical sections on functional programming, functional-logic programming, logic programming, innovative applications, constraint programming and constraint solving, and systems applications.