The 4th International Workshop on Quasi–Elastic Neutron Scattering, QENS '98, was held in Nykoping, Sweden from August 6–8, 1998. Following the tradition of previous meetings, which were held on the grounds of Windsor Castle (UK), in apalace in San Sebastian (Spain) and in a converted farm house on the campus of the University of Parma (Italy), the conference venue was an “old” building, in this case aconverted mill house. There were 40 participants, from a wide variety of disciplines but all with a common interest in techniques, applications and results from quasi-elastic neutron scattering. It was a lively and informal meeting with a lot of discussion.