The International Workshops on Implementation of Functional Languages (IFL) are a tradition that has lasted for over a decade. The aim of these workshops is to bring together researchers to discuss new results and new directions of research related primarily but not exclusively to the implementation of fu- tional or function-based languages. A not necessarily exhaustive list of topics includes: language concepts, type checking, compilation techniques, (abstract) interpretation, automatic program generation, (abstract) machine architectures, arrayprocessing, concurrent/parallelprogrammingandprogramexecution, heap management, runtime pro?ling and performance measurements, debugging and tracing, tools and programming techniques. IFL 2000 was held at Schloß Rahe, an 18th century castle in Aachen, G- many, during the ?rst week of September 2000. It attracted 49 researchers from the international functional language community, presenting 33 contributions during the four days of the workshop. The contributions covered all topics m- tioned above. In addition, a special session organised by Thomas Arts from the Ericsson Computer Science Laboratory in Stockholm, Sweden, attracted several prac- tioners from industry who reported on their experiences using the functional language Erlang. The Erlang session was sponsored by Ericsson Computer S- ence Laboratory. This year, the workshop was sponsored by local industry (Ericsson Eurolab DeutschlandGmbHanddebisSystemhausAachen), whichindicatesthegrowing importanceoffunctionallanguageconceptsincommercialspheres.Wethankour sponsors for their generous contributions.