In the fifty years since the inception of the Society for General Microbiology, the study of pathogenic microbes and the development of methods for their control has been a focus of attention for many microbiologists. This volume reviews the immense progress that has been made during the past half-century. It opens with the text of Sir Alexander Fleming's 1946 Linacre Lecture Chemotherapy: Yesterday, Today and Tomorrow, and then considers the development of key antimicrobial compounds, both naturally occurring and synthetic, active against bacteria, viruses, fungi and protozoa. Contributors also treat broader issues of antimicrobial production, screening, improvements and resistance. Topics such as why epidemics still occur and the need for new antibiotics highlight the fact that, despite the advances, the fight against infection continues unabated.