Cryptosporidium currently presents one of the most pressing challenges for the water industry. High-profile incidents have brought the problem to public attention, yet the technical difficulties of monitoring and eliminating "crypto" are significant. These selected proceedings summarise the work of many of the world's leading experts, who gathered in Paris to establish the state of our knowledge regarding Cryptosporidium, Giardia and other waterborne particles. The 27 papers deal with issues of detection, resource protection, particles separation techniques, disinfection and inactivation, and plant management. They provide essential information for all concerned with these issues whether for scientific research, regulation or utilities management.