Radio phone-in programmes have been the subject of a number of studies using the methodology of conversation analysis. Although this has been successful in making apparent the sequential organization of this type of interaction, little has been said about its categorial organization. Adopting an ethnomethodological approach, it is demonstrated in this article that interaction on public access radio can be seen to rely upon categorial and sequential identities built up and developed upon over the course of interaction. By paying attention to the categorial features within media interaction, together with the sequential organization, it is possible to examine the way identities are reflexively developed in conjunction with the sequential flow of interaction. This in turn allows an analysis able to address the multilayered organizational methods used by members as part of the on-going flow of interaction.