The following technical report is available from http://aib.informatik.rwth-aachen.de/: Sergio Antoy, Yoshihito Toyama (eds.) WRS 04 -- 4th International Workshop on Reduction Strategies in Rewriting and Programming 2004-06 This report contains the proceedings of the 4th International Workshop on Reduction Strategies in Rewriting and Programming (WRS 2004), which was held on June 2, 2004 as part of the Federated Conference on Rewriting, Deduction, and Programming (RDP 2004) in Aachen, Germany.