This paper identifies the different ways in which media developments lead to ever smaller audiences being examined within people meter systems. The consequent unreliability of much people meter data is assessed and strategies proposed for dealing with this. A greater use of aggregation in the use of audiences and trading practices is proposed. Alternative techniques are also considered. A key principle is that the measurement of a number of small audiences in aggregate can be as reliable as the measurement of a large audience. Not only does research have to change but also the use of research.