What can we learn for HIV prevention from John Snow, founder in the 1850s of modern epidemiology? In 1854, convinced that a London cholera outbreak was spread by means other than "miasma", the public health pioneer persuaded authorities to remove a pump handle. Rather than treating the water (a biomedical approach) or persuading people not to use the water (a behavioural approach), this early instance of a structural intervention cut off access to the water source and thus had impact at the level of the community environment. Taking the Broad Street pump as her theme, Chief Executive Dr Lori Heise presents definitions, evidence and arguments to explain STRIVE's approach to HIV prevention.