This book constitutes the refereed proceedings of the 6th International Conference on Algebraic and Logic Programming, ALP '97 and the 3rd International Workshop on Higher-Order Algebra, Logic and Term Rewriting, HOA '97, held jointly in Southampton, UK, in September 1997. The 18 revised full papers presented in the book were selected from 31 submissions. The volume is divided in sections on functional and logic programming, higher-order methods, term rewriting, types, lambda-calculus, and theorem proving methods.