The mission of the Wellcome Trust is 'to promote and foster research with the aim of improving human and animal health'. In this paper the Director of the Wellcome Trust describes the organisation's history, its current position in the UK and international arenas, and the strategies the Trust will pursue in meeting its mission. This includes an explanation of the role of the Trust in enhancing the UK science base by focusing on support of knowledge creation, scientific careers, infrastructure and the translation of research from the laboratory to the clinic, and in promoting the public's appreciation of and confidence in science.