Speakers' Corner is a multicultural setting in a London park at which the general public can actively participate in popular debate. A successful “soap-box” orator should attract and keep an audience, elicit support from the crowd, and gain applause; indeed, a mastery of the crowd, the discourse, and the message is highly valued. However, although talk resources are deployed sensitively by speakers to elicit group affiliation and response, they are also exploitable by hecklers as resources for launching heckles and disaffiliative responses. Audiences at Speakers' Corner are not passive receivers of rhetorical messages; they are active negotiators of interpretations and alignments that may support, resist, or conflict with the speaker's and other audience members' orientations to prior talk. Using transcribed examples of video data recorded at Speakers' Corner, the timing, format, and sequential organization of heckling are described and analyzed with the tools and methods of conversation analysis. (Conversation analysis, audience response, popular public discourse, political speech, heckle)