In this study, we use a conversation analysis framework to understand the systematic organization of interactions in Periscope live video streams, and its crucial features: the talking heads orientation for the video stream, in common with video-mediated communication; the expectation that the streamer should attend to all messages as much as possible; the ‘loose’ organization of viewers’ responses to streamers’ turn-at-talk, as in multi-party chats. We also identify a distinctive design for streamers’ responses to messages, the ‘read-aloud and respond’ practice. (...) These distinctive features are oriented to the highly asymmetrical communicative affordances of Periscope streams. Without precluding other forms of Periscope-based activities, this systematic organization of talk and messages, coupled with the affordances of the application, favors a basic mode of topic initiation resting on a typical and minimal adjacent pair: viewer’s noticing/streamers’ reading and responding. We argue that the particular salience of this organization of topic initiation may account for the emergence of the dominant kind of use for Periscope streams, that is, the online public exposure of youth to strangers in order to elicit some conversation. (shrink)