Broadcasters around the world face similar challenges: how to determine who is listening to their broadcasts, what type of programming appeals to listeners, and how to make their audience share grow. In the United States, an estimated 99.6 million homes were radio-equipped in 1993. Some 209 million receivers were located outside homes. American businesses spent more than 35 billion dollars on advertising, and about one quarter of the advertising dollars were spent for radio. Stiff competition means that U.S. commercial radio broadcasters must sell their audience to advertisers. Similarly, noncommercial broadcasters must fight for program sponsorship. Broadcasters seeking an edge over the competition look beyond traditional diary and survey audience data. Domestic firms specializing in marketing and audience research technology are developing new data-gathering technologies and methods to help radio broadcasters better reach and understand their audiences. Radio stations throughout the ideas and opinions expressed in this paper are the authors and do not reflect the point of view of the U.S. Information Agency or the U.S. Government.