This book constitutes the refereed proceedings of the 9th International Symposium on Functional and Logic Programming, FLOPS 2008, held in Ise, Japan, in April 2008.

The 20 revised full papers presented together with 3 invited contributions were carefully reviewed and selected from 59 submissions. The papers are organized in topical sections on constraints, constructive arithmetic, dependent types, rewriting, program transformation, logic and lambda-calculus, types, and debugging.