The portable people meter (PPM) is a promising new media research tool that makes it possible to automatically track consumersâ exposure to the electronic media. An inaudible code is inserted into the audio signal of radio, television, cable and other media outlets. These codes are then detected by pager-sized personal meters worn by respondents. As a follow-up to the successful PPM test panels fielded in Manchester, England during 1998- 2000, Arbitron Inc. launched a large-scale market trial and demonstration of the PPM system in the Philadelphia area in the United States in late 2000. Phase One of the trial is being conducted with a panel of 300 persons aged 6 years and older in the Wilmington, Delaware Arbitron Radio Metro. Initial installation of the panel was completed in March 2001. This paper reports preliminary results from the trial covering cooperation, panel representativeness and respondent compliance with the PPM methodology. Results to date suggest that consumers in the United States, like those in the United Kingdom, comply with the PPM âwear or carryâ instructions to a high degree.