Particle accelerators, originally developed for basic research, have matured into versatile tools for important applications in other branches of science as well as in medicine and industry. The first IAEA International Symposium on Utilisation of Accelerators, 26-30 November 2001 in Sao Paolo, Brazil, brought together 135 international experts in the field and covered all aspects of accelerator technology and applications, with invited presentations on topics such as synchrotron radiation, environmental and industrial applications.