ISIS is the world's most powerful pulsed spallation source, providing beams of neutrons and muons that enable the structure and dynamics of condensed matter to be probed on a microscopic scale that ranges from the subatomic to the macromolecular. The source was approved in 1977 and the first neutrons were produced in late 1984. ISIS was first described in Neutron News Vol. 1. No. 1 in 1990 and this article is an update, emphasizing the developments of the last five years. ISlS operates a large user program with experiment selection based around two submission rounds per year in April and October. Full details on applying for ISIS beam time can be obtained from the University Liaison Secretatiat at the ISlS Facility, Rutherford Appleton Laboratory, Chilton, Didcot, Oxon, 0x11 OQX, UK (Tel: +44 1235 445592; Fax: +44 1235 441235445103).