For many years, researchers have explored digital support for photographs and various methods of interaction around those photos. Services like Instagram, Facebook, and Flickr have demonstrated the value of online photographs in social media. Yet we know relatively little about these new practices of mobile social photography and in-situ sharing. Drawing on screen and audio recordings of mobile photo app use, this paper documents the ephemeral practices of social photography with mobile devices. We uncover how photo use on mobile devices is centered around social interactions both through online services, but also face-to-face around the devices themselves. We argue for a new role for the mobile photograph, supporting networks of communication through instantaneous interactions, complemented with rich, in person discussions of captured images with family and friends; photography not for careful selection and archive, but as quick social play and talk. The paper concludes by discussing the design possibilities of ephemeral communication.