Although scholars have investigated the ways youths individually enact composing practices and the impact of audience on these practices, this study examines the impact of an audience physically present while composing in a shared, public space--an ambient audience. Blurring the line between traditional notions of audience and collaborator through a process of distributed co-construction with individual composers, the ambient audience proved generative for the composing work of individuals. This article highlights two examples of this distributed co-construction in action: the co-constructed framing of everyday experiences as the topic for created videos and the shared aesthetic of juxtaposition that the youth participants co-constructed while composing individual images. The results of this study suggest future research and development of instructional approaches that address the social nature of composing with a specific look at the ways publics influence processes of composing.