The present volume is the Proceedings of the 18th International Conference on Nearrings and Nearfields held at the Helmut-Schmidt-Universität, Universität der Bundeswehr Hamburg, from July 27 – August 3, 2003. It contains the written versions of the lectures by the five invited speakers. These concern recent developments of planar nearrings, nearrings of mappings, group nearrings and loop-nearrings. One of them is a long and very substantial research paper The Z-Constrained Conjecture. They are followed by 13 contributions reflecting the diversity of the subject of nearrings and related structures. Besides the purely algebraic structure theory these papers show many connections of nearring theory with group theory, combinatorics, geometries, and topology. They all contain original research.