The Eighteenth European Frequency and Time Forum (EFTF) took place on 5-7 April 2004. It is an international conference and exhibition providing information on recent advances and trends of scientific research and industrial development in the fields of frequency and time. The fact that time can be measured so precisely, far better than any other physical parameter, represents a technological asset of great importance. Many space programmes and terrestrial applicationsrequire some form of stable timing for successful operation. Typical examples are digital network synchronisation, spread spectrum communication, range and range-rate determination, navigation and position location, very long baseline interferometry, scientific research (gravity and relativity experiments), time transfer by satellites, earth observation and geodesy.